Count Alphabets Digits and Symbols in a String

Question

Problem: Count Alphabets Digits and Symbols in a String. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 
#include 

void classify_chars(const char *str, uint8_t *alpha, uint8_t *digit, uint8_t *symbol) {
    *alpha = 0;
    *digit = 0;
    *symbol = 0;

    uint8_t i = 0;
    while (str[i] != '\0') {
        char ch = str[i];
        if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
            (*alpha)++;
        } else if (ch >= '0' && ch <= '9') {
            (*digit)++;
        } else if (ch != ' ') {
            (*symbol)++;
        }
        i++;
    }
}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);
    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '
') {
            str[i] = '\0';
            break;
        }
        i++;
    }
    uint8_t alpha = 0, digit = 0, symbol = 0;
    classify_chars(str, &alpha, &digit, &symbol);
    printf("Alphabets = %u
Digits = %u
Symbols = %u", alpha, digit, symbol);
    return 0;
}

What is this about?

Basic parsing problem that mimics real firmware needs like command validation, serial input checks, or debugging interfaces.

Why it matters in firmware?

ctype.h may not be available or used due to overhead
MCU serial handlers often need raw character classification
Helps structure CLI, command parser, or telemetry checks

Solution Logic

Use ASCII ranges:
- A-Z = 65 to 90
- a-z = 97 to 122
- 0–9 = 48 to 57
Any other non-space character is a symbol

95. Count Alphabets Digits and Symbols in a String