Check if the String Numeric or Alphabetic

Code

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

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

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