#include <stdio.h>
#include <ctype.h>
int main()
{
char c, result;
c = 'M';
result = tolower(c);
printf("tolower(%c) = %c
", c, result); // tolower(M) = m
c = 'm';
result = tolower(c);
printf("tolower(%c) = %c
", c, result); // tolower(m) = m
c = '+';
result = tolower(c);
printf("tolower(%c) = %c
", c, result); // tolower(+) = +
return 0;
}