Introduction

C program to change string to upper case without strupr. I have used Code:: Blocks compiler for debugging purpose. But you can use any C programming language compiler as per your availability.

#include <stdio.h>

   void functionupper(char []);

   int main()
   {
      char string[100];

      printf("Enter a string to convert it into upper case\n");
      gets(string);

      functionupper(string); // calling functionupper

      printf("Entered string in upper case is \"%s\"\n", string);

      return 0;
   }

   void functionupper(char s[]) {
      int c = 0;

      while (s[c] != '\0') {
         if (s[c] >= 'a' && s[c] <= 'z') {
            s[c] = s[c] - 32;
         }
         c++;
      }
   }

Result