Reverse any String in C

Reverse any String Program in C

Reverse of String means reverse the position of all character of any String. For example reverse of porter is retrop.

#include<stdio.h>
#include<conio.h>
#include<string.h>

void main()
{
 char str[100],temp;
 int i,j=0;
 clrscr();
 printf("Enter any the string :");
 gets(str);  //  gets function for input string
 i=0;
 j=strlen(str)-1;
  while(i<j)
   {
   temp=str[i];
   str[i]=str[j];
   str[j]=temp;
   i++;
   j--;
   }
 printf("Reverse string is :%s",str);
 getch();
}

Enter any the string  : hitesh
Reverse string is : hsetih

Explanation Of Program :

Firstly find the length of the string using library function strlen().

j = strlen(str)-1;

Suppose we accepted String "hitesh" then

j = strlen(str)-1;
  = strlen("hitesh") - 1
  = 7 - 1
  = 6

As we know String is charracter array and Character array have character range between 0 to length-1. Thus we have position of last character in variable 'j'.Current Values of 'i' and 'j' are :

i = 0;
j = 6;

'i' positioned on first character and 'j' positioned on last character. Now we are swapping characters at position 'i' and 'j'. After interchanging characters we are increment value of 'i' and decrements value of 'j'.

while(i<j)
     {
     temp   = str[i];
     str[i] = str[j];
     str[j] = temp;
     i++;
     j--;
     }

If i crosses j then process of interchanging character is stopped.