Reverse a String in C ~ GNIITHELP

Program to Reverse a String

Following is the program to Reverse a String using for loop.

#include<stdio.h>
#include<conio.h>
void main()
{
   int i, j, k;
   char str[100];
   char rev[100];
   printf("Enter a string\t");
   scanf("%s", str);
   printf("The original string is %s", str);
   for(i = 0; str[i] != '\0'; i++);
   {
      k = i-1;
   }
   for(j = 0; j <= i-1; j++)
   {
      rev[j] = str[k];
      k--;
   }
   printf("The reverse string is %s", rev);
   getch();
}

Output

Enter a string  studytonight
The original string is studytonight
The reverse string is thginotyduts

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Program to Reverse a String using Recursion

Now let's reverse a string using recursion.

#include<stdio.h>
#include<conio.h>
char* reverse(char* str);

void main()
{
   int i, j, k;
   char str[100];
   char *rev;
   printf("Enter a string\t");
   scanf("%s", str);
   printf("The original string is %s", str);
   rev = reverse(str);
   printf("The reverse string is %s", rev);
   getch();
}

char* reverse(char *str)
{
   static int i=0;
   static char rev[100];
   if(*str)
   {
      reverse(str+1);
      rev[i++] = *str;
   }
  return rev;
}

Output

Enter a string  studytonight
The original string is studytonight
The reverse string is thginotyduts