Computer system

Program using strcat() function.

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{

char str1[10]="jbrec";

char str2[]="ece";

strcat(str1,str2);

printf("%s\n",str1);

printf("%s\n",str2);

getch();

}



OUTPUT : jbrecece

ece

7 : strrev(string) - String Reverse :This function is used to reverse a string. This function takes
only one argument and return one argument.

Syntax : strrev(string);

Ex : Program using strrev() function

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{


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,char str[20];

printf("Enter the string:");

scanf("%s",str);

printf("The string reversed is:%s",strrev(str));

getch();

}



OUTPUT : Enter the string :subbareddy

The string reversed is : ydderabbus



UNIT – III


FUNCTIONS:




User‐Defined Functions

Definition: A function is a block of code/group of statements/self contained block of statements/
basic building blocks in a program that performs a particular task. It is also known
as procedure or subroutine or module, in other programming languages.

To perform any task, we can create function. A function can be called many times. It
provides modularity and code reusability.

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, Advantage of functions

1) Code Reusability

By creating functions in C, you can call it many times. So we don't need to write the same code
again and again.

2) Code optimization

It makes the code optimized we don't need to write much code.

3) Easily to debug the program.


Example: Suppose, you have to check 3 numbers (781, 883 and 531) whether it is prime number or
not. Without using function, you need to write the prime number logic 3 times. So, there is repetition of
code.

But if you use functions, you need to write the logic only once and you can reuse it several times.



Types of Functions

There are two types of functions in C programming:

1. Library Functions: are the functions which are declared in the C header files such as
scanf(), printf(), gets(), puts(), ceil(), floor() etc. You just need to include appropriate
header files to use these functions. These are already declared and defined in C
libraries. oints to be Remembered

System defined functions are declared in header files

System defined functions are implemented in .dll files. (DLL stands for Dynamic Link
Library).

To use system defined functions the respective header file must be included.

2. User-defined functions: are the functions which are created by the C programmer, so
that he/she can use it many times. It reduces complexity of a big program and optimizes
the code. Depending upon the complexity and requirement of the program, you can create
as many user-defined functions as you want.




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