#include<stdio.h>
#include<string.h>
main()
{
char s[100];
printf("enter the string in lower case");
gets(s);
strupr(s);
printf("the string in upper case letters is:");
puts(s);

}
     
           
Note: Need to be arranged in compiler after copied
   

 OutPut:

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