PasswordChecker.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "password_checker.h"

/* Declare conditions */
char upperCases[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
    'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
    'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};

char lowerCases[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
    'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
    's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};

char specials[] = {'`', '!', '\"', '?', '$', '?', '%', '^', '&',
    '*', '(', ')', '_', '-', '+', '=', '{', '[',
    '}', ']', ':', ';', '@', '\'', '~', '#', '|',
    '\\', '<', '>', '.', '?'};

char numbers[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

/*
 * Function: CheckPasswordHealth
 * ----------------------------
 *   Check password health.
 *   pPassword: Password string.
 *   returns: Return -1: password length is smaller than 10 characters.
 *            Return 0: password contains invalid characters.
 *            Return 1 or return 2: password health is low.
 *            Return 3: password health is medium.
 *            Return 4: password health is strong.
 */
int CheckPasswordHealth(char *pPassword) {
    int pLength = strlen(pPassword);
    char invalid[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
        'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
        'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
        'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
        's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '`', '!', '\"', '?', '$', '?', '%', '^', '&',
        '*', '(', ')', '_', '-', '+', '=', '{', '[',
        '}', ']', ':', ';', '@', '\'', '~', '#', '|',
        '\\', '<', '>', '.', '?', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
    if (pLength < 10)
        return -1;
    else
        if (pLength > 20)
        return 5;
    else {
        int i, Count = 0;
        char *checkInvalid, *checkUp, *checkLow, *checkSpecial, *checkNum;
        for (i = 0; i < pLength; i++) {
            checkInvalid = strchr(invalid, pPassword[i]);
            if (checkInvalid == NULL)
                return 0;
            break;
        }
        for (i = 0; i < pLength; i++) {
            checkUp = strchr(upperCases, pPassword[i]);
            if (checkUp != NULL) {
                Count++;
                break;
            }
        }
        for (i = 0; i < pLength; i++) {
            checkLow = strchr(lowerCases, pPassword[i]);
            if (checkLow != NULL) {
                Count++;
                break;
            }
        }
        for (i = 0; i < pLength; i++) {
            checkSpecial = strchr(specials, pPassword[i]);
            if (checkSpecial != NULL) {

                break;
            }
            return 0;
        }
        for (i = 0; i < pLength; i++) {
            checkNum = strchr(numbers, pPassword[i]);
            if (checkNum != NULL) {
                Count++;
                break;
            }
        }
        return Count;
    }
}

int main() {
    printf("========== Password health checker ==========\n");
    printf("This program is to check password health with 3 levels: ");
    printf("low, medium and strong.\nEnter password ");
    printf("(password must be no smaller than 10 and no larger than 20): ");
    char *psswd;
        scanf("%50[^\n]s", psswd);
//    gets(psswd);

    int checker = CheckPasswordHealth(psswd);
    if (checker == -1)
        printf("Your password length is smaller than 10 characters.");
    else if (checker == 0)
        printf("Your password contain invalid characters.");
    else if (checker == 1 || checker == 2)
        printf("Your password health is low.");
    else if (checker == 3)
        printf("Your password health is medium.");
    else if (checker == 4)
        printf("You password health is strong.");
    else if (checker == 5)
        printf("Your password length is larger than 20 character.");
}