99. Check if the String Numeric or Alphabetic

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

void classify_string(const char *str) {
    int index = 0;
    int numeric = 0;
    int alpha = 0;

    while (str[index] != '\0') {
        char ch = str[index];
        if (ch >= '0' && ch <= '9') {
            // we have a digit
            numeric = 1;
        } else if ((ch >= 'A' && ch <= 'Z') || ch >= 'a' && ch <= 'z') {
            // we have a letter
            alpha = 1;
        } else {
            // we have a symbol
            printf("MIXED");
            return;
        }
        if (alpha && numeric) {
            // we have a mixture of digits and letters
            printf("MIXED");
            return;
        }
        index++;
    }

    if (numeric) {
        printf("NUMERIC");
    } else if (alpha) {
        printf("ALPHABETIC");
    } 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;
}