Check if the String Numeric or Alphabetic

Code

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

void classify_string(char *str){
    int alphabetic = 0, numbertic = 0, mixed = 0;
    int len = strlen(str);
    for(int i = 0; i<len; i++){
        if((str[i] >= '0')&&(str[i] <= '9')){
            numbertic++;
        }
        else if(((str[i] >= 65)&&(str[i] <= 90))||((str[i] >= 97)&&(str[i] <= 122))){
            alphabetic++;
        }
        else{
            mixed++; 
        }
    }   
        if(((numbertic)&&(alphabetic))||(mixed)){
            printf("MIXED");
        }
        else if((alphabetic == 0)&&(numbertic)){
            printf("NUMERIC");
        }
        else if((alphabetic)&&(numbertic == 0)){
            printf("ALPHABETIC");
        }
}

int main(){
    char str[100];
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0';
    classify_string(str);

    return 0;
} 

Solving Approach