Mengulang kembali ke Validasi Input Pengguna C

Sepertinya kasus untuk perulangan do {...} while(...) . Kata "lainnya" yang Anda cari ada tepat setelah pencarian kamus.

Sunting: Ini akan berfungsi seperti ini:

do {
  /* read password here */
  ...
  if (condition not met) {
    printf("condition not met!\n");
    continue;
  }
  if (another condition not met) {
    printf("another condition not met!\n");
    continue;
  }
  ...
} while(0);

Edit2: Mungkin ada baiknya melakukan pengujian pada fungsi lain seperti ini:

bool password_is_safe(char *password)
{
  ...
  if (condition not met) {
    printf("condition not met!\n");
    return false;
  }
  if (another condition not met) {
    printf("another condition not met!\n");
    return false;
  }
  ...
  return true;      
}

  /* in another function */
  ...
  do {
    ...
    /* read password here */
    ...
  } while(!password_is_safe(password));

Ini membuatnya lebih mudah untuk memahami logika program tanpa harus menggulir ke atas dan ke bawah.

Sunting3:

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

#define STRINGIFY(x) #x
#define STRINGIFY_VALUE(x) STRINGIFY(x)

#define MAX 80

static bool test_and_complain(const bool test, const char *complain)
{
    if (test) {
        printf("%s\n", complain);
    }
    return test;
}

static void write_history(const char *password)
{
    FILE *f = fopen("passHistory.txt", "w");
    // always check if fopen() was successful
    if (!f) {
        fprintf(stderr, "can't write password history\n");
        exit(EXIT_FAILURE);
    }
    fprintf(f, "%s\n", password);
    fclose(f);
}

void validatePass()
{
    char password[MAX+1];
    int iUpper,iLower,iSymbol,iNumber,iTotal;

    //shows user password guidelines
    printf("\n\n\t\tPassword rules: ");
    printf("1. Passwords must be at least 9 characters long and less than 15 characters.");
    printf("2. Passwords must have at least 2 numbers in them.");
    printf("3. Passwords must have at least 2 uppercase letters and 2 lowercase letters in them.");
    printf("4. Passwords must have at least 1 symbol in them (eg ?, $, £, %%).");
    printf("5. Passwords may not have small, common words in them eg hat, pow or ate.");

    // loop until we got a good password
    bool pw_invalid;
    do {
        //gets user password input
        printf("Enter your password following password rules: ");
        // Security risc:
        // Never ever use "%s" without specifying a length!
        // scanf("%s", password);
        scanf("%" STRINGIFY_VALUE(MAX) "s", password);

        countLetters(password,&iUpper,&iLower,&iSymbol,&iNumber,&iTotal);

        // Notice that you could eliminate the boolean variable and
        // wrap all the tests in a single expression and put
        // that inside the loop condition of the loop.
        // I think it looks nicer this way though.
        // Notice that the || operator does not evaluate the right hand
        // expression if the left hand expression evaluates to true.
        // I.e. after the first test fails, no other tests are performed.
        // This is equivalent to the if-else cascade from before.
        pw_invalid = false;
        pw_invalid = pw_invalid || test_and_complain(
                      (iUpper < 2),
                      "Not enough uppercase letters!!!");
        pw_invalid = pw_invalid || test_and_complain(
                      (iLower < 2),
                      "Not enough lowercase letters!!!");
        pw_invalid = pw_invalid || test_and_complain(
                      (iSymbol < 1),
                      "Not enough symbols!!!");
        pw_invalid = pw_invalid || test_and_complain(
                      (iNumber < 2),
                      "Not enough numbers!!!") ;
        pw_invalid = pw_invalid || test_and_complain(
                      (iTotal < 9),
                      "Not enough characters!!!");
        pw_invalid = pw_invalid || test_and_complain(
                      (checkWordInFile("dictionary.txt",password)==gC_FOUND),
                      "Found your word in the dictionary");
        pw_invalid = pw_invalid || test_and_complain(
                      (checkWordInFile("passHistory.txt",password)==gC_FOUND),
                      "You already used this password recently");
    } while(pw_invalid);

    printf("\nYour new password is verified\n");
    // Security risc:
    // Never ever use a user supplied string as a format string!
    // printf(password);
    printf("%s\n", password);

    //writing password to passHistroy file.
    write_history(password);

    printf("\n\n\n");
    system("pause");
} //end validatePass method

Jika ini adalah pekerjaan rumah, silakan periksa kembali nilai Anda. ;-)

Gunakan goto. Ini adalah salah satu dari sedikit kasus yang dibenarkan.

Berikut ini contohnya. Seperti yang Anda lihat, ini jauh lebih bersih daripada while(0), dan akan membuat kompiler lebih sedikit mengeluh dengan -Wall juga!

// Returns whether or not the condition failed, printing the
// given error if it did.
static bool verifyThat(bool condition, const char* error) {
    if(!condition) printf("%s", error);
    return !condition;
}

void validatePass()
{
    FILE *fptr;
    char password[MAX+1];
    int iChar,iUpper,iLower,iSymbol,iNumber,iTotal,iResult,iCount;

    //shows user password guidelines
    printf("\n\n\t\tPassword rules: ");
    printf("\n\n\t\t 1. Passwords must be at least 9 characters long and less than 15 characters. ");
    printf("\n\n\t\t 2. Passwords must have at least 2 numbers in them.");
    printf("\n\n\t\t 3. Passwords must have at least 2 uppercase letters and 2 lowercase letters in them.");
    printf("\n\n\t\t 4. Passwords must have at least 1 symbol in them (eg ?, $, £, %).");
    printf("\n\n\t\t 5. Passwords may not have small, common words in them eg hat, pow or ate.");

    get_user_password:

    printf("\n\n\t\tEnter your password following password rules: ");
    scanf("%s", &password);

    iChar = countLetters(password,&iUpper,&iLower,&iSymbol,&iNumber,&iTotal);
    iUpper = ...
    iLower = ...
    iSymbol = ...
    iNumber = ...
    iTotal = ...

    if(verifyThat(iUpper >= 2, "Not enough uppercase letters!!!\n")
          || verifyThat(iLower >= 2, "Not enough lowercase letters!!!\n")
          || verifyThat(iSymbol >= 1, "Not enough symbols!!!\n")
          || verifyThat(iNumber >= 2, "Not enough numbers!!!\n")
          || verifyThat(iTotal >= 9, "Not enough characters!!!\n")
          || verifyThat(iTotal <= 15, "Too many characters!!!\n"))
        goto get_user_password;

    iResult = checkWordInFile("dictionary.txt", password);

    if(verifyThat(iResult != gC_FOUND, "Password used."))
        goto get_user_password;

        printf("Your new password is verified.");
}