Count Alphabets Digits and Symbols in a String

Code

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

void classify_chars(const char *str, uint8_t *alpha, uint8_t *digit, uint8_t *symbol) {
    int n_alpha = 0;
    int n_digit = 0;
    int n_symbs = 0;
    int index = 0;
    while (str[index] != '\0') {
        char c = str[index];
        if ('a' <= (c | 0x20) && 'z' >= (c | 0x20)) // convert to lower case
            n_alpha++;
        else if ('0' <= c && '9' >= c)
            n_digit++;
        else
            if (c != ' ')
                n_symbs++;

        index++;
    }
    *alpha = n_alpha;
    *digit = n_digit;
    *symbol = n_symbs;
}

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++;
    }

    uint8_t alpha = 0, digit = 0, symbol = 0;
    classify_chars(str, &alpha, &digit, &symbol);
    printf("Alphabets = %u\nDigits = %u\nSymbols = %u", alpha, digit, symbol);
    return 0;
}

Solving Approach