Check if the String Numeric or Alphabetic

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

void classify_string(const char *str) {
    // Your logic here
    int i = 0;
    /*
    while(str[i] != '\0'){
        if((str[i] >= 'A' && str[i] <= 'Z') || (str[i] >= 'a' && str[i] <= 'z')){
            if(str[i + 1] >= '0' && str[i + 1] <= '9'){
                return "MIXED";
            }
        }
    }
    */
    if((str[i] != '\0') && str[i] >= '0' && str[i] <= '9'){
        while(str[i] >= '0' && str[i] <= '9'){
            if(str[i + 1] != '\0' && (str[i + 1] <= '0' || str[i + 1] >= '9')){
                printf("MIXED");
                return;
            }
            i++;
        }
        printf("NUMERIC");
        return;
    }
    if((str[i] != '\0') && ((str[i] >= 'A' && str[i] <= 'Z') || (str[i] >= 'a' && str[i] <= 'z'))){
        while((str[i] >= 'A' && str[i] <= 'Z') || (str[i] >= 'a' && str[i] <= 'z')){
            if((str[i + 1] != '\0') && ((str[i + 1] < 'A') || (str[i + 1] > 'z') || ((str[i + 1] > 'Z') && (str[i + 1] < 'a')))){
                printf("MIXED");
                return;
            }
            i++;
        }
        printf("ALPHABETIC");
        return;
    }

}

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;
}