Check if the String Numeric or Alphabetic

Code

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

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