Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
    // Your logic here
    int digit = 0, letter = 0, length = 0;
    while (*str != '\0') {
        if ('0' <= *str && *str <= '9') 
            digit++;
        else if (('A' <= *str && *str <= 'Z') || ('a' <= *str && *str <= 'z')) 
            letter++;
        str++;
        length++;
    }
    if (digit == length && letter == 0) 
        printf("NUMERIC");
    else if (digit == 0 && letter == length)
        printf("ALPHABETIC");
    else
        printf("MIXED");
}

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++;
    }

    classify_string(str);
    return 0;
}

Solving Approach