Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
   int i=0,n=0,a=0,k=0;
   while(str[i] != '\0')
   {
    if(str[i]>='A' && str[i]<='z') a=1;
    else if(str[i]>='0' && str[i]<='9') n=1;
    else
     {
        k=1;
        break;
     }
     i++;
   }
   //printf("%d %d %d\n",k,a,n);
   if(k==1) printf("MIXED");
   else if(n==1 && a==1) printf("MIXED");
   else if (n==0 && a==1) printf("ALPHABETIC");
   else if (n==1 && a==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