Convert Uppercase Letters to Lowercase

Code

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

void to_lowercase(char *str) {
    /*
    uint32_t i = 0;
    while (str[i] != '\0') {
        char c = str[i];
        if (c >= 'A' && c <= 'Z')
            str[i] = c | 0x20;
        i++;
    }
    */
    for (char c = *str; c != '\0'; c = *str++) {
        if (c >= 'A' && c <= 'Z')
            *(str-1) = c | 0x20;
    }
}

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;
}

Solving Approach