Core Interview Questions: February 2013

Thursday, 14 February 2013

The exit() Functions in C Programming Language

In case of any file input-output error or erroneous command line arguments, it is possible to terminate program execution. This can be done through the exit() function as shown in the following example: if( argc!= 3){printf("Invalid arguments\n");exit();} An integer may also be passed as a parameter to the exit() function. In UNIX, this value is stored in the environmental variable "$?", and should be in the range 0 - ...

The stdin, stdout and stderr FILE type Pointers

The stdin, stdout and stderr are names used to refer to the standard input device (keyboard) and standard output and error device (VDU). These are actually FILE type pointers, defined in the file stdio.h, and can be used with file input-output functions. For example, the following statement: fputc (c, stdout); writes the value of the char type variable c onto the VDU. The standard input, output and error files are not...

The NULL Return Value in C Language

In case fopen() is unsuccessfull in opening a file, it send s back a null(zero) value called NULL. NULL is defined in the file stdio.h. For example, the following statement. if((fp = fopen ("a.dat", "r")) == NULL) can be used to test whether the file a.dat has been opened successfully or not....

Closing Files in C Programming Language

Closing Files Each file is closed by one fclose() statement as shown in the following code: #include<stdio.h>main(){::fclose(ptr1);fclose(ptr2);} The above code is used to close files. fclose() statement is used to close files...

Reading from and writing to Files in C Language

In C, character input-output functions from files are simple extensions of the corresponding functions for input-ouput from/to the terminal. So, there are funcitons such as: fgetc()fputc() The only additional parameter of both functions is the appropriate file pointer, so that the file to be used for input-output is known. The following code performs the actual copying of contents of a.dat to b.dat: #include<stdio.h>main(){char...

Opening Files in C Language

The C statements that would do this are: #include<stdio.h>main(){FILE *ptr1, *ptr2;ptr1 = fopen ("a.dat", "r");ptr2 = fopen ("b.dat", "w");--------} The function fopen() opens a file in the appropriate access mode. When a file is opened, certain information regarding that file automatically gets stored in different variables. These variables are collectively classified as the data type FILE. fopen() returns a pointer...

File Handling in C Programming Language

The treatment of files in C is very simple, unlike that of other programming languages where there are special in-built and often rigid file structures and file-handling routines. C treats file input-output in much the same way as input-output from/ to the terminal, and provides file input-output functions, very similar to those for input-output from/to the terminal. The simplicity of the input-output in C lies in the fact...

sprintf(), sscanf() Functions for Formatting Data in Memory

The formatting functions available as part of the standard library for formatting data in memory, are: -> sprintf() ->sscanf() These functions, like printf() or scanf(), write variables to a destination or read data for variables from a destination. The difference is that while printf() writes to the screen, sprintf "writes" to a variable in the memory. Similarly while scanf() reads from the keyboad into variables,...

atoi(), atof() Standard String to Numeric Conversion Functions

atoi() This function returns the int type value of a string passed to it and the value() in case the string does not begin with a digit. For example, if the array str1 contains the string "1234", then the following statement: y = atoi(str1); will cause y to have the value 1234. However, if the array str1 contains the string "ABC", then the following statement: y = atoi(str1); will cause y to have the value(). atof() This...

Standard String - Handling Functions in C

A brief description of some of the standard string functions of C given below, strcmp() strcmp() compares 2 strings (its parameters) character by character (ASCII comparison) and returns any of the integer values. less than(), greater than(). strcpy() strcpy() copies the second string to the first string named in the strcpy() parameters. For example, the following statement: strcpy (str1, "ABC"); will copy the string...

SURROGAT cLASS in z/OS Mainframe System

A surrogate user can submit jobs on behalf of another user without having to specify the original user's password. The Original user specified on the job card. Job submitted by the surrogate users execute with the authority of the original user. The output of the job owned by the commands. -> RDEF SURROGAT RAM.SUBMIT UACC(NONE) NOTIFY(RAM). -> SETR RACLIST(SURROGAT) REFRESH -> PERMIT RAM SUBMIT CLASS(SURROGAT)...

How to Delete General Resource Profiles ?

The following command are used to delete the general resource profiles. -> RDELETE|RDEL cls_name prfl_name. -> RDEL OPERCMDS MVS.DISPLAY.PDS. RACLIST RACLIST is list of frequently accessed profiless maintained in real storage....

How to Protect General Resource Profiles

The RDEFINE Command is used to define the general resource profile to the RACF database. -> RDEF OPERCMDS MVS.DISPLAY.PDS UACC(NONE) NOTIFY(DFSMS) -> SETR RACLIST(OPERCMDS) REFRESH -> PERMIT MVS.DISPLAY.** CLASS(OPERCMDS) ID(MFADMIN) ACCESS(READ) -> RALTER OPERCMDS MVS.DISPLAY.** NOTIFY(RAM) Listing the General Resource Profiles -> RLIST OPERCMDS MVS.DISPLAY.** -> RLIST OPERCMDS MVS.DISPLAY.** ALL...

Listing dataset Protection in z/OS Mainframe

LISTDSD command is used to list a dataset profile defined to RACF. -> LISTDSD ID(ram) - will give info about perticular ID. -> LISTDSD ID(ram) all -> LISTDSD dataset('sys1.parmlib') -> LISTDSD dataset('sys1.parmlib') all Removing Dataset Protection The DELDSD command is used to delete the dataset profiles defined to the RACF database. -> DELDSD|DD prfl_name -> DELDSD 'sys.**' Refreshing Dataset...

Dataset Profiles - Resource Profile in Mainframe

Datasets can be protected using dataset profile. a). Discrete Dataset A Discrete dataset profile protects only a single dataset. Usually very sensitive datasets are protected using discrete dataset profile. Creating a Dataset Profile -> ADDSD 'usr001.Jcl.ps' UACC(NONE) NOTIFY(usr001) Permit userID to access the datasets. -> PE 'usr001.JCL.ps' ID(Demo06) ACCESS(UPDATE) Change Access Authority. -> ALTDSD 'usr001.JCL.ps'...

Resource Profile in z/OS Mainframe Systems

Resource profile is used to protect the resources. There are three types of REsource profiles. 1. DataSet Profiles Datasets can be protected using dataset profile. a. Generic Dataset A generic dataset profile protects more than one datasets. Generic dataset profiles than one datasets. Generic dataset & profiles exploit the similarity in the name of the datasets. More about Dataset Profiles 2.General Resource Pr...

RACF Users in Mainframe Computer Systems

The functional elements of RACF are users and groups. RACF users are identified by alphanumeric userID. IBMUSER is a default user and it is a member of group SYS1. 1. Adding new users. -> ADDUSER|AU user01 name(main75) password(UNA) dfltgrp(grp) owner(demo006) 2. Add user with TSO segment. -> ALU user01 tso(proc(ikjdb2) acctnum(acct#) size(4096)) 3. Deleting users used to delete user from RACF Group -> DELUSER|DU...

RACF Groups in Mainframe Computer Systems

Groups are RACF Entities with which you associate any number of users. SYS1 is the highest group which is predefined when RACF is installed. All groups other than SYS1 have a Superior group. 1. Adding new groups The ADDGROUP command is used to define new groups to RACF. -> ADDGROUP|AG grp supgroup(sgroup) owner(demo06). 2. Listing groups The LISTGRP command is used to list information about a RACF defined group. ->...

RACF - Resource Access Control Facility - Mainframe System

RACF is the IBM Security Management product for mainframe operating system. RACF - Extream Security Manager(ESM). Profile - RACF stores all this information about users groups and resources in profiles. A profile is a record of RACF information that has is a record of RACF inforamtion that has been defined by the security administratior. There are 3 profiles. 1) User Profile An individual member identified by his unique...

z/890 SHUT DOWN Procedure in Mainframe Systems

Issue the following commands one by one from the master console. 1. P TCPIP 2. C CICS1 3. -Stop DB2 4. P TSO 5. Z NET 6. F BPXOINIT, SHUTDOWN = FORKINIT 7. C LLA - Library look aside facility 8. C VLF - Virtual look aside facility 9. F DLF, MODE = DRAIN - Data look aside facility. 10. P DLF 11. P RMF 12. P FFST - First Failure Support Technology. 13. %STOP - Racf 14. C SYSLOGD1 15. $P INIT - Initiators 16....

IPL Start up Procedure in z/OS Mainframe System

1. Switch on the HMC and login to the HMC Control or Interface Panel. 2. Then, Click the "Groups" Icon in the "view" section and than click the "CPC Images Icon in the Work area. 3. Select the appropriate LPAR on which you have to load the MVS image and finally, Double Click on the Activate button in the Daily panel which is at the right pane of the HMC window. 4. Similarly, select the LPAR on which you have to load the...

Types of IPL ( Initial Program Load ) in z/OS Mainframe

1) Cold Start Any IPL that loads or reloads the PLPA and does not preserve the VIO data sets. The first IPL after system installation is always a cold start because the PLPA is initially loaded. Note - IPL with CLPA option. 2) Quick Start Any IPL that does not reload the PLPA and does not preserve the VIO data sets. Nore - IPL with CVIO option. 3) Warm Start Any IPL that does not reload the PLPA and preserve the jourhaled...

IPL Phases in z/OS Mainframe System

Hardware IPL Phase The volume where the OS is stored is refered to as the SYSRES volume or the IPLable disk. IRIM Phase IPL Resource Initialization Model. The IRIM reads the LoADPARM information. The LOADPARM consists of IODF volume number, LOADxx version, IPL prompt feature and the alternate nucleus id. NIP Phase Expands the SQA and the extended SQA creates the pageable link pack area and extended PLPA Loads modules...

IPL - Initial Program Load in z/OS Mainframe

- Loading the Operating System to the Main Storage or Main Memory. - Load Nucleaus to the SysRes Volume. - Starting the LPAR is called IPL. Power ON Reset (POR) Power ON Reset is performed the system reads the IOCDS and checks the connectivity of all hardware devices. IPL Phases in z/OS Hardware IPL pahse IRIM phase NIP phase MSI phase Subsytem Initialisation Phase More about IPL Phase...

GDG - Generation Data Group in z/OS mainframe system

Generation Data groups or GDG's are a group of data sets which are related to each other chronologically and functionally. These related Data sets share a unique Data set name. Every GDG data set has a Generation number and version number assigned to each data set. Example: 'MYLIB.LIB.TEST.G0001V00' 'MYLIB.LIB.TEST.G0002V00' 'MYLIB.LIB.TEST.G0003V00' Creation of GDG Before using GDG, we need to create GDG index and model....

IBM Mainframe Interview Questions

1) What is Control Area ? A group of Control Intervals makes up a control area. Max size - 1 cylinder, Min size - 1 Track. 2) What is Control Interval Split ? Not enough space in the control interval the control interval split is happens. 3) What is Control Area Split ? If no free CI's found in CA it will go for the split of control area. 4) What is GDG ? Generation Data Groups or GDG's are a group of data sets which...

Control Interval (CI) in z/OS Mainframe System

VSAM groups Individual Data records in to larger units of storage. These units of storage are called Control Intervals. A Control Interval is the amount of data transfered between the auxiliary storage and virtual storage. Control Interval has 4 components. 1) Data 2) Control Interval Descriptor Field (CIDF) 3) Record Descriptor Field (RDF) 4) Free Space. CIDF - Contains the information about the free space within the...

Mainframe Interview Questions for freshers

1) What is cluster ? A cluster is the collection os physical datasets that make up one logical dataset. 2) What is Relative Byte Address ? The RBA of a record is its displacement from the begining of data set. 3) What is Index ? Locate the exact Information. 4) What is Control Interval ? VSAM groups individual Data records in to larger units of storage. These units of storage are called Control Intervals. 5) What is...

Data Sets in VSAM - Virtual Storage Access Method

Entry Sequenced Data Set Records in an ESDS are stored in the order in which they are written and are retrived by addressed access. ESDS is a sequential VSAM data set. Key Sequenced Data set - KSDS Rrecords in a KSDS are stored in key sequence and are controlled by an index, determine the order in which records are stored. In KSDS, records can be processed both sequentially and randamly. Relative Record Data Sets - RRDS Records...

VSAM - Virtual Storage Access Method in z/OS mainframe System

VSAM is a Data Management System, it is a high performance Access Method. VSAM acts as an interface between processing programs and the operating system. Access Method Access Methods are ways to maximize the efficiency of data storage and retrieval. Access Method Types 1) Queued Sequential Access Method : QSAM 2) Basic Sequential Access Method : BSAM 3) Index Sequential Access Method : ISAM 4) Basic Direct Access Method...

Procedures - Proc and Pend Statements in z/OS

There are two statements, 1) Proc Statement Marks the begining of a Procedure, Optional for a cataloged procedure, Required for an Instream Procedure. 2) Pend Statement Marks the End of a Procedure. Name is Optional for a cataloged procedure, Required for an Instream Procedure. Symbolic Parameters A symbolic parameter is a symbol proceded by an ampersand that stands for a parameter, subparameter or value. Marks the...

Procedures in z/OS Mainframe Operating System

A procedure is a set of standard JOB step definitions that can be used repeatedly to perform a function. Procedures are collection of executable Instruction. Procedures are Invoded by EXEC Statements. There are two types of Procedures, They are 1) Cataloged Procedure Cataloged Procedure is a set of Job Control Statements that are grouped together, given a name, then recorded as a member of a partitioned data set. 2)...

Keyword Parameters in DD Statements

The following Keyword parameters are generally using, a) DCB The DCB parameter defines the format type, length of records, and block size for a new data set. b) DSN which is an accepted abbreviation for the DSNAME, which identifies the real name of a data set. c) DISP which identifies the data set as a new data set ( The Current status of the dataset). d) SPACE The space parameter allocates storage for a new data set...

Positional Parameters in DD Statements

In Positional parameters, four parameters are there, They are a) Instream Data (*) The * parameter value begins in-stream data set. b) Data The DATA parameter value begins an in-stream data set that may contain statements with // in columns 1 and 2/ c) Dummy The DUMMY parameter value tells z/OS not to perform any I/O, or disposition processing on the data set. d) DYNAM The DYNAM parameter value is supported only to...

DD (Data Definition) Statement in Job Control Language

It describes data sets to be used with in individual steps. There are two parameters in DD statement. They are, 1) Positional Parameters In Positional Parameters, four parameters are there, a) Instream Data (*) b) Data c) Dummy d) DYNAM More about Positional Parameters 2) Keyword Parameters In Keyword Parameters, six and more parameters are there, a) DCB b) DSN c) DISP d) SPACE e) LABEL f) SYSOUT g) UNIT More about...

Positional Parameters in EXEC Statement

There are two parameters are there. They are, a) PGM The PGM parameter identifies the program the system is to run. b) PROC The Proc or procedure name identifies the cataloged or in-stream procedure the system is to run. Keyword Parameters in EXEC Statement There are three parameters are there. They are, a) PARM Passes parameters to the program that is being executed. b) REGION Use the REGION parameter to override...

EXEC Statements in Job Control Language

EXEC Statement It marks the begining of a job step and specifies the name of the program to be executed. There are two parameters of EXEC Statements. They are i) Positional Parameters Positional parameters are having two type of parameters. a)PGM b)PROC And You can see the topic Positional Parameters in EXEC Statement ii) Keyword Parameters Keyword Parameters are having three parameters called PARM, REGION, and CO...

Keyword Parameters in Job Statement

a) CLASS CLASS specifies the jobs Class. Indicates the type of JOB submitted to the system. Example: CLASS = A -> test jobs B -> production jobs b) MSGCLASS Determines the output device to which system messages and JCL messages are written. Normally A for printer, T for Terminal. c) MSGLEVEL MSGLEVEL = (JCL , allocations) MSGLEVEL specifies the printing of JCL statements and allocation messages. JCL...

Positional Parameters in JOB Statement

There are two positional parameters are there a) Job Accounting Information Identifies account number which will be billed for CPU time. b) Programmer Name Identifies the author's name. Example: (1989, Name) where, 1989 - Account Number Name - Authors Name...

JCL Statements in Mainframe Systems

There are three types of JCL Statements are there, 1. JOB 2. EXEC 3. DD 1. JOB Statement It marks the begining of a job and identifies the job name. Job Statement contains two parameters, a) Positional Parameters b) Keyword Parameters Positional Parameters There are two positional parameters are there. They are, i. Job Accounting Information ii. Programmer Name More About Positional Parameters...

JCL - Job Control Language in Mainframe

JCL - Job Control Language provides the operating system with information about the resources, programs and data neccessary to complete the job. JCL acts as an interface between programs written in COBOL and Operating System. What is JOB? Collection of unit of tasts is called JOB. Batch Processing - is used to execute one or more programs in a specified sequence with no further interaction by a user. What are JCL Statements...

Wednesday, 13 February 2013

Returning Values from a Function in C programming

Just as data can be passed to a function, so also, data can be passed back from a called function to its caller. In C, functions can return values through the return verb as illustrated in the following example: main(){int x, y, value;scanf("%d %d", &x, &y);fflush(stdin);value = sun(x,y);printf("Total is %d \n", vlaue);}sum (a,b)int a,b;{return a + b;} In this example, the function sum() sends back the value of...

Passing Arrays to Functions in C Programming

Arrays are inherently passed to functions by the call by reference method. for instance, if an array called num_array of size 10 is to be passed to a function called stringfunc(), then it would be passed as follows: stringfunc (num_array); Recall that num_array is actually the address of the first element of the array. So, this would be a call by reference. The parameter of the called function, say, number_list could be...

Call by Reference in C Programming Language

Call by reference means that the called function should be able to refer to the variables of the caller function directly, and not create its own copy of the values in different variables. This would be possible only if the address of the variables are passed as parameters to the function. Consider the same program written using call by reference: main(){int num1, num2;char operator;printf("Enter 2 numbers and an operator\n");scanf("%d%d%c",...

Invoking Functions in C Programming Language

In C programs, functions that have parameters are invoked in one of two ways: 1). Call by value 2). Call by reference These will be illustrated through the example of a program called computer that takes two numbers and a mathematical operator as input and perfoms the appropriate arithmetic operation on the numbers. Call by Value Consider the following code for the problem statement memtioned: main() { int num1,num2; char...

Parameter of a Function in C Programming

The term 'parameter' has been introduced earlier. To review, consider the following printf() statement: printf("%d", value); The printf() function expects two pieces of information: 1. The format(s) in which data is to be printed. 2. The variable(s) whose value(s) is/are to be printed in the specified format(s). These are the parameters of the function printf(). Thus, parameter(s) of a function is/are the data that the...

What is Functions in C Programming Language ?

Functions are the building blocks of C. All programs definitely consist of one function - main() - and inevitably refer to, or, in programming terminology, call or invoke standard functions of C such as printf(), scanf(), etc. as well as user-defined functions. Advantages of Functions Besides the obvious advantages of -> Reusability, and -> Structing of programs functions also provide programmers a convenient way...

String - Handling Functions Using Pointers C Programming Language

Now that we have laid the groundwork for understanding the concept of pointers, we will write a few functions to manipulate strings using pointers. #include <stdio.h>main(){char *ptr,str[20];int size=0;printf("\nEnter String :");gets(str);fflush(stdin);for(ptr=str; *ptr != '\0' ; ptr++){size++;}printf("String length is %d", size);...

Two Dimensional Arrays and Pointers in C Programming language

Extending the logic of declaring one-dimensional character arrays, we can also declare two-d charater arrays. char *things[6]; Individual strings can be initialised by separate assignment statements since each element of this array is a pointer. things[0] = "Raindrops on roses"; things[1] = "And Whiskers on kittens"; things[2] = "Bright copper kettles"; things[3] = "And Warm woollen mittens"; things[4] = "Brown paper packages...

Pointer Arithmetic of incrementing and decrementing

Arithmetic operations of incrementing and decrementing can be performed on pointers. In fact, pointer arithmetic is one of the reasons why it is essential to declare a pointer as pointing to a certain datatype so that when the pointer is incremented or decremented, it moves by the appropriate number of bytes. Thus, a simple satement like ptr++; does not neccessarily mean that ptr now points to the next memory location. What...

Two Dimensional Character Arrays in C Programming Language

Two-d character arrays are typically used to create an array of strings. Manipulating a character two-d array is however, slightly different from manipulating an integer or float two-d array. This is because a character two-d array is likely to be accessed in terms of strings rather than elements, and hence requires only the row subscript. Individual elements can be accessed as usual by specifying both subscripts. Consider...

What is Task and Transaction in Mainframe Systems

Task - The tast is a unique, basic unit of work scheduled by the OS or CICS. A task can, * Read from and write to the terminal. * Read and write files. * start another task. Transaction A transaction is an entity which initiates execution of a task. In CICS, every transaction is identified by a 4 character transaction identifiers (TRANSID). The transaction IDs are placed in the DCT by the system programmer. CICS Features...

CICS Nucleus in Mainframe Computer System

1) The CICS Nucleus consits of a set of control programs and control tables. 2) The control programs are supplied by IBM. 3) The Control tables are userdefined. IBM suplied Control Programs a) DFHSIP b) DFIHTCP c) DFHSCP d) DFHFLP User defined Control tables 1) PPT 2) FCT 3) TCT 4) TST 5) DCT 6) JCT 7) PCT Defining resouces into the control tables add a new entry into the control tables. The resouces entries can be...

CICS System Services

1) Data Communication Fuctions Interface between CICS and terminals, To Interface Telecommunication access methods. To free application programs from the terminal hardware. 2) Data Handling Functions Interface between the CICS and Data, To Interface with data access methods -VSAM, To Interface with databases Access Methods - DB2. 3) Application Programming Services Interface between the CICS and Application Program (COBOL) 1)...

CICS - Customer Information Control System

1) CICS is an Online Transaction Processing System 2) CICS acts as an Interface b/w Application software and z/os. 3) CICS is an Database / Datacommunication control system. CICS Introduction: Macro level CICS - Initial version assembler macro to request CICS services. Command level CICS - High level language version, commands to requests CICS services. What is CICS ? CICS is a transactional subsystem of z/os that...

Protechting data through RACF

1) Add RAcF groups to control datasets that use the default DB2 qualifiers. 2) Create generic profiles for different types of DB2 datasets and permit their use by DB2 started tasks. 3) Permit use of the profile...

DB2 Security in Mainframe Computer Systems

DB SEcurity: 1)Primary Authorization ID 2)Secondary Authorization ID 3)SQLID These three security methods are eligible to secure data access. Method 1: You can secure data access by means of privilleges either specific functions. The privillege can be implicit or explicit. Method 2: You can secure your DB2 dataset access by means of implimenting RACF. Method 3: You can secure DB2 data access by means of encryption...

Starting and Stoping DB2 Databases

Starting DB2 Databases: RW - Allows programs to read from and write to the database. RO - This Read Only. UT - This access code only allows access to this database by DB2 utility programs. FORCE - This option is seldom used, as it does not generate database integrity. Stoping DB2 Databases STOP DATABASE (*) - stops all database which you have the authority to stop. STOP DATABASE(database name) stops the one database specified. STOP...

Controlling the IRLM in Mainframe

The IRLM monitors and manages the mechanism that DB2 uses to ensure databases integrity. This mechanism is known as locking. The IRLM, which DB2 connected to, is defined in the DB2 parameter member DSNZPARM in SYS1.PARMLIB. The name identified in this member is the IRLM procedure name and is used as part of the OS/390 modify(F) command. The following OS/390 commands are used to manage the IRLM. F procname, ABEND, NODUMP. Requests...

Console Authority in Mainframe

Auth specifies the group of operator commands that can be entered from the console. You can change the AUTH using Vary command the syntax is as follows VARY CN(console-id), AUTH=<authority> There are six types of authority they are as follows * MASTER * INFO * SYS * IO * CONS * ALL MASTER indicates that this is a console with master-level authority. The system uses the first online console in CONSOLXX with MASTER...

Console Monitoring in Mainframe Computer system

Computer operators are responsible for monitoring and managing the operations of MVS. Computer operators use consoles to * Issue system commands * Receive system messages Consoles cannot be used for any other input/output purposes (such as TSO, CICS, etc.). MVS sends messages via the console that * Informs you the status of the job * Request that you perform a required action, such as mounting tapes or catridges Consoles...

OS/390 Storage in Mainframe system

Logicaly an OS/390 system consists of DASD, one or more CPUs and I/O devices. Central or Main Storage - is directly addressable by CPU where both programs and data must be loaded before processing. Expanded Storage - may be used to relieve the central storage when it is heavily utillized. This is done by moving data from the central to the expanded storage. The combination together is called processor storage. The storage...

Basic Mainframe Technical HR Interview Questions

What is Mainframe Storage Management ? Storage Management is basically provided through OS/390's operating system MVS which organizes the available storage in such a way that the usable storage appears to be larger than what is actually available. To accomplish this it provides various mechanisms to move data and programs between different kinds of storage thereby virtually enlarging the storage for each user. What is Workload...

Introduction to OS/390 - Mainframe System

An IBM System 390 consists of hardware and software products. The hardware has a central processor complex (CPC) that includes the central processor, storage, channels etc. The Software consists of system application programs, end-user application tools etc. The primary program executing on the system is an operating system is an operating system such as OS/390. The OS/390 operating system manages the instructions to be processed...

Basic Interview Questions in Database - DBMS

What is Hierarchical Database System ? Hierarchical database system keeps the data in teh form of a parent child relationship. The datas is organised as a Tree structure. The origin of a data is the root of the data tree. The data occupies with different level of the particular branch of the tree called the node. The last node in the structure is called leaf. The high level node points to zero or more node in the next level....

What is Database Models ?

Database models is a technique to store the database in a DBMS. Each DBMS follows different database model. Database models can be classified into two groups. They are, 1) Object - based logical model 2) Record - based logical model 1) Object - based logical model : In this model, the data, relationship and constraints are defined as a collection of ideal tools. 2) Record - based logical model : This model describes the...

Relationship between data in Database Management System

Relationship is an association between the entities. A relationship may associate an entity with itself. There are are four different types of relationships among the entites. They are, 1) One - to - One 2) One - to - Many 3) Many - to - One 4) Many - to - Many One - to - One Relationship in Database Management System A relationship between one entity to only one other entity is called One - to - One relationship. One...

Entity & Attributes in Database Management System

Entity in Database Management System An entity is an object or a thing such as person, place, concept, activity about which an Organization keeps information. Graphically entity is represented as a rectangle with name. Example: in College system Student, teacher etc, are called entity. Attributes in Database Management System An attribute is the characteristic properties of an entity. It describe the entity. Graphically...

Services of Database Management System

A DBMS provides the following servicess to do the activities mentioned previously. Let us see some of the services. 1. Data Definition: This is a method of defining data and its storage. 2. Data maintenance: This method verifies whether each record has fields containing all information as defined using data definition. 3. Data Manipulation: Data manipulation allows to insert, update, delete and sort data in the database. 4....

What is RDBMS in Database concepts

RDBMS is stands for Relational DataBase Management System. Proper management of data is very essential to run any concern successfully. Before the emergence of RDBMS , all are used DBMS to manage data. But most of the concerns felt that DBMS to was not efficient to meet their expectations. As a result, application developers began to move their attention to other environment like COBOL and C. What is DataBase Management System A...

Interview Questions - Data Structure

1) What is the significance of a Primary key? 2) What is the primitive data type ? 3) What are the data structure operations ? 4) What is an linear array? 5) What is an two dimensional array? 6) What is a pointer? 7) How Strings are represented in memory? 8) How 2D arrays are represented in memory? 9) Explain Pointer array? 10) Distinguish linear search and binary search. 11) Explain the concept of binary search. 12) Explain...

String Operations in C Programming Language

String is a sequence of characters in c programming. The important string operations are, 1) Substring 2) Indexing 3) Concatenation 4) Length Substring in C Programming Language A group of consecutive characters in a string is called substring. The following three attributes are required to identify the substring in a string. 1) name of the string 2) starting position of the substring 3) length of the substring. The general...

Constants & Variables in C Programming Language

String constant is a sequence of characters within single or double quotation marks. Example: 'Welcome' "Welcome" Variables in C Programming Language Each programming language has its own rules for representing character variables. There are three types of variables. They are, 1) Static 2) Semistatic 3) Dynamic Static Variables in C programming Language A static data type is a data type whose length of variable is fixed...

Pointers in C programming Lnaguage

Pointers are variables that hold the memory address of other variables. This can be explained by the following int a = 5; Let us assume that 1001 is the address of the variable a and this numeric address is stored in another variable named as b having address 1020. We can access the values of variable a by using the pointer variable b. Advantages of Pointers in C Programming 1) Pointers increase the execution speed of...

Two dimensional array representation

In many applications the data has to be represented as rows and columns. The representation of data in memory as rows and columns is called 2-D array. The general form is datatype name[row size][column size]; Range : The size of the row is called row range and size of column is called column range. the maximum elements in a 2-D array are got by multiplying row range and column range. Maximum elements in a 2-D array =...

Two types of Data Structures to store data ?

Ther are thow types of data structures to store data. They are, 1) Linear 2) Non-linear Linear DataStructure: In linear data structure, data items are organized in a sequential or in linear list order. There are two ways to represent linear structure in memory. They are, 1) Arrays 2) Linked list In an arrays structure the data items are represented by contineous memory locations. In linked list structure the data items...

Data Structure Operations

Operation means processing the data in the data structure. The following are some important operations. 1) Traversing - to visit or process each data exactly once in the data structure. 2) Searching - to search for a particular value in the data structure for the given key vlaue. 3) Inserting - to add a new value to the data structure 4) Deleting - to remove a value from the data structure 5) Sorting - to arrange the values...

Tuesday, 12 February 2013

What is Data Structure or Data Oraganization ?

Oraganization refers the way in which the data is represented or stored in the memory. This is also called data structure. Data can be oraganized in many ways. They are, 1) Primitive data types 2) Arrays 3) Linked List 4) Trees 5) Graphs 6) Files If the data contains a single value, this can be organized as a primitive data type. If the data contains a set of same data type values, then this can be organized consecutively...

Files in Data Structure and Data Organization

A file is a collection of related records (entity). Each record contains a set of fields (attributes). Each field refers a numeric or non-numeric values. A set of minimun number of attributes which are used to idendify a record in a file is called key (primary key). What is Data Structure or Data Oraganization ? Oraganization refers the way in which the data is represented or stored in the memory. This is also called data...

What is Primitive Data Types in Data Structure ?

What is Primitive Data Types in Data Structure ? The different primitive data types are 1) integer 2) float 3) double 4) character 5) boolean Using this we can represent a single value. The range of values in each primitive data type is different in different computer languages. For example in C language the range of integer value is -2^31 to 2^31 - 1. ...

Symbolic constants and constant qualifiers in C++ programming

Symbolic constants and constant qualifiers in C++ programming Symbolic constant is a quantity which does not change during the execution of the program. Constant qualifiers are keywords used to define a quantity as symbolic constant. The qualifiers are 1) const. 2) enum. steps and rules: 1) Const must be initialized. 2) Const is local to the function where it is declared. 3) By the qualifier extern along with const, it...

What is Typedef in C++ programming ?

What is Typedef in C++ programming ? Typedef is a keyword. This is used to define a new name for an existing data type. The general form is typedef datatype newname; where, typedef -keyword datatype - valid datatypes such as int, float, char, etc. new name - valid C++ name for the data type In C++ there is no need to specify the keyword typedef for enum, structure and union data types...

Difference between unions and structures

Difference between unions and structures 1) A union can provide storage for one member at a given time. But a structure can provide storage for all members. 2) The amount of space allocated for union is based upon the member which requires the largest memory space. But in structure each member is given memory space. 3) In Union at one time we can refer any one variable. But in structure we can refer all the variables. ...

Union in C++ programming Language

Union is like a structure data type in which all the members share the same memory area. The general form is, union tag-field { datatype member1; datatype member2; ------ ------ datatype membern; }variable1, variable2 ...variablen; Example: Consider the following union declaration union example { char name[15]; int number; }student; This declares student as a variable to the union named example having two members. The members...

Structre in C++ Programming Languages

A structure is defined as a data type to represent different types of data with a single name. The data items in a structure are called members of the structure. Defining a structure: A structure definition contains a keyword struct and a user defined tag-field followed by the members of the structure within braces. The general form is struct tag-field { datatype member1; datatype member2; ------- ------- datatype membern; } where, struct...

Advantages of Enumeration in c++ Programming

Advantages of Enumeration in c++ Programming a. With this we can assign more than one constant value to a single user defined name. b. Internally the values of constant are 0, 1, 2, ... n-1. c. We can explicitly change the value of constants. d. Arithmetic operations are possible on enumerated type variables....

User defined data types in C++ Programming Language

User defined data types are data types defined by the user. They are 1) Enumeration 2) Structure 3) Union 4) Class 1) Enumeration This allows us to define our own data type with predefined values. The general form is, enum userdefined_name { value1, value2, --- --- valuen }; The default values 0,1,2,.... n-1 can be changed by giving value in the declaration as enum userdefined_name { value1=20, vlau2=3 .... valuen=50...

Type Casting in C++ Programming Language

It is a process of converting one data type into another. There are two types of data type conversion. They are, 1) Explicit conversion 2) Implicit conversion 1) Explicit conversion It is a process of converting one data type into another explicitly using cast operator. The general form is newtype (variable or expression); (or) (new type) variable or expression; 2) Implicit conversion or automatic conversion If an...

Data types in C++ Programming Language

C++ data types can be classified as 1) Basic data types 2) User defined data types 3) Derived data types Basic data types in C++ Programming Language These data types are already defined in the language. They are, 1) char 2) int 3) float 4) double The following keywords are prefixed with the basic data types to produce new data types. These keywords are otherwise called as modifiers. 1) signed 2) unsigned 3) long 4) short Special...

Constants in C++ Programming Language

Constant is a quantity which does not change during the execution of the program. The different type of constants are, 1) Integer constant 2) Floating point constant 3) Character constant 4) String constant 5) Wide - character constant Example: 345 - Integer 110.21 - Floating point 'B' - Character constant "Name" - String constant A 'CD' - Wide character constan...

Dynamic initialization of variables

Initialization of variables during run time is called dynamic initialization of variables. Example: int l; cin>>l; float avg=l/10; The variable avg is initialized only during run time, because the value of l is available during run time only....

Declaration of variables in C++ Programming Language

Variable is a quantity which changes during the execution of the program. All variables present in the program must be declared before it is used. The declaration can also be done before the first use of the variable. The general for is datatype variablelist; Example: 1) int a, b, c; This declares a, b, c as integer variables and allocate memory space. 2) int n; for(int j=0; j<=n;j++) This is valid because j is declared...

Identifiers in C++ Programming Language

Identifiers are names given to variables, functions, arrays and other user defined structure. These are user defined names. Steps (how to do): 1) Identifiers are formed with alphabets, digits and a special character underscore (-). 2) The first character must be an alphabet. 3) No special characters are allowed other than underscore. 4) They are case sensitive. That is AA is different from aa. 5) There is no limit for the...

Commenting and UnCommenting a Program C Programming

Comment statements are non-executable statements. These statements are used to increase the readability and understanding of the program. A comment statement can be included anywhere in the program. There are two types of comments. they are, 1) Multiline comment 2) Singleline comment All multiline comments should start with /* and end with */. No space is allowed between * and /. All singleline comments should start...

Namespace in C++ Programming Language

Namespace is a keyword used to create a memory area. In this area the programmer can define various program elements such as variables, functions, classes etc. These program elements can be used any where in the programs like global variables. Defining a namespane The general form is, namespace name { statement-1; statement-2; --------- statement-n; } ...

Keywords in C and C++ Programming Language

Keywords are words which belongs to C++ language. They have standard predefined meaning. These words should be used only for their intended purpose. The users have no right to change its meaning. Keywords should be written in lowercase. New keywords in C++ C++ language contains all the keywords in C language. In addition to this some more keywords are added to make C++ language as an object oriented language. These keywords...

Tokens in C++ Programming Language

A token is an individual element in a program. More than one taken can appear in a single line separated by white spaces. White space may be blank, carriage return or tab. The possible C++ tokens are 1) keywords 2) identifiers 3) constants 4) operators 5) string...

Manipulators in C++ Programming Language

Manipulators are functions used with the insertion operator (<<). These are used to format the data to be displayed. They are, 1) endl 2) setw 1) endl - end line This function is used to transfer the control to a new line while printing. Example: cout<<"Name :"<<name<<endl<<"Age"<<age; 2) setw - set width This function is used to set the width of the output list. The list may be variables...

cout and cin objects in C++ Programming

cout object cout is an object. It is predefined in the headerfile iostream.h. It is used to display the information on the VDU. The general form is, cout << list to be printed; When this statement is executed, the list on the right hand side of the operator << is directed to the object cout and displayed on the VDU. Rules for cout objects: 1) This should terminate with semicolon (;) 2) If the list to be printed...

Structure of C++ Programs - For Beginers

Include file In C++ there are a number of files called header files. These files contain number of predefined functions, classes, variables and data. If we want to use the predefined functions, classes, variables and data in our program, the appropriate header file should be included at the beginning of the program. The general form of include file is #include<headerfilename.h> Examples : iostream.h, fstream.h, graphic.h,...

What is Main Difference C++ have from C ?

C++ is an object oriented language. It is an extension of C language. C++ compiler supports both C and C++. The following important features are added with C to make it C++. 1) Class 2) Inheritance 3) Polymorphism 4) Function overloading 5) Operator overloading 6) Data hiding Software development using C language supports top down structured approach. But C++ language supports bottom-up and object oriented approach....

Advantages of Object Oriented Programming

1) Resuability In OOP's, programs, fuctions and modules that are written by a user can be reused by other users without any modification. 2) Code sharing In OOP's, the programmer can share the codes which are common to more than one class by definng it in the parent classes in hierarchical order. 3) Data hiding In OOP's, the programmer can hide data and functions in a class from other classes. 4) Reduced complexity of a...

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Thursday, 14 February 2013

Wednesday, 13 February 2013