string.toupper code example

Example: toupper

#include 
#include 
int main() {
    char c;

    c = 'm';
    printf("%c -> %c", c, toupper(c));

    c = 'D';
    printf("\n%c -> %c", c, toupper(c));

    c = '9';
    printf("\n%c -> %c", c, toupper(c));
    return 0;
}