Check if the String Numeric or Alphabetic

Code

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

void classify_string(const char *str) {
    uint8_t alphabet_present=0, num_present=0;
    int i=0;
    if(str[0]=='\0')
    {
        printf("MIXED");
        return;
    }

    while(str[i] !='\0')
    {
        if((str[i]>='A' && str[i]<='Z') || (str[i]>='a' && str[i]<='z'))
        {
            alphabet_present=1;
        }
        else if(str[i]>='0' && str[i]<='9')
        {
            num_present=1;
        }
        else
        {
            printf("MIXED");
            return;
        }
        i++;
    }
    if(alphabet_present==1 && num_present==0)
    {
       printf("ALPHABETIC");
    }
    else if(alphabet_present==0 && num_present==1)
    {
        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