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

int main(void) 
{ 
   int length, i; 
   char *string = "THIS IS A STRING"; 

   length = strlen(string); 
   for (i=0; i<length; i++) 
   { 
       string[i] = tolower(string[i]); 
   } 
   printf("%s\n",string); 

   return 0; 
}