Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
    bool containsDigits = false;
    bool containsAlpha = false;
    while(*str != '\0'){
        if((*str >= 'A' && *str <= 'Z') || (*str >= 'a' && *str <= 'z')){
            containsAlpha = true;
        }else if(*str >= '0' && *str <= '9'){
            containsDigits = true;
        }else{
            printf("MIXED");
            return;
        }
        str++;
    }
    if((containsAlpha + containsDigits) == 2)
        printf("MIXED");
    else if(containsAlpha)
        printf("ALPHABETIC");
    else if(containsDigits)
        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