c - 循环回到用户输入验证 C

Question

我有以下方法来生成必须满足要求的字符串，但如果不满足验证要求，我需要某种子句来循环回用户输入。我知道在 Java 中有后续读取，但我我不确定 C 中所需的代码是什么，如果任何人都能发现错误，我也不认为我的 else if 语句语法正确。一些提示或建议会有所帮助，谢谢。

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.");

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


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

    if(iUpper < 2)
    {
        printf("Not enough uppercase letters!!!\n");


    }
    else if(iLower < 2)
    {
        printf("Not enough lowercase letters!!!\n");


    }
    else if(iSymbol < 1)
    {
        printf("Not enough symbols!!!\n");


    }
    else if(iNumber < 2)
    {
        printf("Not enough numbers!!!\n");


    }
    else if(iTotal < 9 && iTotal > 15)
    {
        printf("Not enough characters!!!\n");


    }

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

    if( iResult == gC_FOUND )
    {
        printf("\nFound your word in the dictionary");
    }
    else if
    {
        printf("\nCould not find your word in the dictionary");
    }

    iResult = checkWordInFile("passHistory.txt",password);
    else if( iResult == gC_FOUND )
    {
        printf("\nPassword used");
    }
    else if
    {
        printf("\nOk to use!");
    }
    else
    {
    printf("\n\n\n Your new password is verified ");
    printf(password);
    }
    //writing password to passHistroy file.


    fptr = fopen("passHistory.txt", "w");   // create or open the file
    for( iCount = 0; iCount < 8; iCount++)
    {
        fprintf(fptr, "%s\n", password[iCount]);
    }

    fclose(fptr);

    printf("\n\n\n");
    system("pause");


}//end validatePass method

Answer 1

使用 goto。这是为数不多的少数情况之一。

这是一个例子。正如您所看到的，它比 while(0) 干净得多，并且也会使编译器对 -Wall 的提示更少!

// 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.");
}