#include<stdio.h>
main()
{
char s[50];
int i;
printf("enter a string");
gets(s);
i=0;
while(s[i]!='\0')
{
if(s[i]>=97&&s[i]<=122)
{
s[i]=s[i]-32;
}
i++;
}
printf("the string in upper case letters is:");
puts(s);
}
     
           
Note: Need to be arranged in compiler after copied
   

 OutPut:

enter a string computer the string in upper case letters is:COMPUTER