Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
    char isalpha = 0, isnum = 0, isother = 0;
    while (*str)
    {
        if ((*str >= 'a' && *str <= 'z') || (*str >= 'A' && *str <= 'Z'))
            isalpha = true;
        else if (*str >= '0' && *str <= '9')
            isnum = true;
        else
            isother = true;
        str++;
    }
    if (isother || isalpha == isnum)
        printf("MIXED");
    else if (isalpha)
        printf("ALPHABETIC");
    else if (isnum)
        printf("NUMERIC");
}

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