96. Convert Uppercase Letters to Lowercase

#include <stdio.h>
#include <stdint.h>

void to_lowercase(char *str) {
    // Your logic here
    uint8_t diff = 'A' - 'a';
    while (0 != *str) {
        if ('A' <= *str && *str <= 'Z') {
            *str = *str - diff;
        }
        str++;
    }
}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    to_lowercase(str);
    printf("%s", str);
    return 0;
}

I caculated the diff between uppercase and lowercase.