Checksum Validate

A checksum condenses several input characters into one value that can be checked.

checksum_validate.c

#include <stdio.h>

int digitChecksum(const char *text) {
    int sum = 0;
    for (int i = 0; text[i] != '\0'; i++) {
        sum += text[i] - '0';
    }
    return sum;
}

int main(void) {
    int useAlt = ;
    const char *digits = useAlt ? "1235" : "1234";
    int expected = 10;
    int checksum = digitChecksum(digits);
    int ok = checksum == expected;

    printf("useAlt=%d digits=%s checksum=%d ok=%d\n", useAlt, digits, checksum, ok);
    return 0;
}

#include <stdio.h>

int digitChecksum(const char *text) {
    int sum = 0;
    for (int i = 0; text[i] != '\0'; i++) {
        sum += text[i] - '0';
    }
    return sum;
}

int main(void) {
    int useAlt = ;
    const char *digits = useAlt ? "1235" : "1234";
    int expected = 10;
    int checksum = digitChecksum(digits);
    int ok = checksum == expected;

    printf("useAlt=%d digits=%s checksum=%d ok=%d\n", useAlt, digits, checksum, ok);
    return 0;
}

checksum The loop accumulates each digit into a compact validation total.

expected value The final comparison turns the checksum into an explicit pass or fail status.