Reverse a String In-Place

#include <stdio.h>

void reverse_string(char *str) {
    if (str == NULL || *str == '\0')
    {
        return;
    }

    char * srart = str; 
    char * end = str;
    while (*end != '\0')
    {
        end++;
    }
    end--;

    while (srart < end)
    {
        char temp = *srart;
        *srart = *end;
        *end = temp;
        srart++;
        end--; 
    }

}

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

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

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