Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
    // Your logic here
    if (str[0]=='\0') {
        printf("MIXED");
        return; 
    }
    uint8_t j=0; 
    uint8_t digit =0;
    uint8_t alpha =0;  

    while (str[j]!='\0') {
        char ch = str[j]; 
        if (ch>='0'&&ch<='9') {
            digit=1; 
        } 
        else if (ch>='A'&&ch<='Z' || ch>='a'&&ch<='z' ) {
            alpha =1; 
        }
        else {
            printf("MIXED");
        return; 
        }
        j++;
    }
    if (digit&&!alpha) printf("NUMERIC");
    else if (!digit&&alpha) 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