How to call my function within parameters in my class (C++)

Question

Hello I'm wondering how I can call functions within parameters in my class in main?

class processChoice {
public:
    void processInput(string, int, string, int);
};

void processChoice::processInput(string processInput_UN, 
                                 int processInput_PC, 
                                 string initial_UN, 
                                 int initial_PC) {
    for (; (processInput_UN != initial_UN) || (processInput_PC != initial_PC);
        cout << endl) {

        cout << "Enter your username: " << flush;
        cin >> initial_UN;

        cout << "Enter your 4 digit pincode: " << flush;
        cin >> initial_PC;

        cout << endl;

        if ((processInput_UN == initial_UN) && (processInput_PC == initial_PC)) {
            cout << "Access granted!" << endl;
        } else {
            cout << "Username and/or pincode doesn't match, try again..."
                << endl;
    }
}

int main() {

    userPinchoice Choice;
    Choice.chooseUsername();
    Choice.choosePincode();

    cout << endl;

    initial Values;
    Values.initialUsername();
    Values.initialPincode();

    processChoice Input;
    Input.processInput();

    return 0;

What am I suppose to put in the round brackets at Input.processInput()? I have been trying to get it to work but I just can't seem to access the function. I'm new to this so any help would be welcome.

Thanks in advance!

You've got a lot going on here that is incorrect. You might want to learn more about C++ syntax before tackling functions / classes. And those round brackets are called parenthesis, by the way. — bejado, Mar 03 '17 at 00:27
Downvoted. Reason: Stack Overflow isn't here to teach programming. — IInspectable, Mar 03 '17 at 00:31
Too many errors. You should take one of the many courses online, or get a book, on c++. The very syntax of your code makes no sense at some points. — BusyProgrammer, Mar 03 '17 at 00:33
Two options: Continue slamming your head against a wall every time you have a problem that can easily be solved by [reading the first few pages of a good book on C++](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) or [read a good book on C++](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). I strongly recommend the second option. — user4581301, Mar 03 '17 at 00:33

score 1 · Answer 1 · answered Mar 03 '17 at 01:24

The bulk of your problem lies in the class processChoice. Here are some of such errors:

Firstly, the parameters specified in the function declaration in your class is faulty:

 void processInput(string, int, string, int);

Here, you have only specified 4 data types, not variables. Kee in mind, these are variables that store the data that is passed from another function. In order to do this, you need to have these variables declared in the above line, variables with specific names that can be identified inside a function. You should have this line in your function declaration:

 void processChoice::processInput(string processInput_UN, int processInput_PC, string initial_UN, int initial_PC)

This brings up another problem. Your function header is diffent upon declaration, and its header is different upon defining. The compiler sees it as 2 different functions. Therefore, you should keep your function headeer the same when declaring it and defining it.

Secondly, the for-loop inside your function has syntax errors:

 for (; (processInput_UN != initial_UN) || (processInput_PC != initial_PC);
    cout << endl) {

Firstly, judging from the syntax of the condition statement of the loop, it should be a do-while loop, not a for loop. Secondly, the cout << endl; should not be inside the condition statement of the for-loop; it should be implemented with the rest of the function. Thirdly, you do not put a semicolon at the end of your condition statement; it tells the compiler that this an empty loop without a body. Your loop should be something like:

 do
 {
     cout << endl; // this is where you put the cout statement

     // add rest of function code here
 }
 while ((processInput_UN != initial_UN) || (processInput_PC != initial_PC))

Another side note, why do you need 4 input parameters in your function? You take the pin number and username as input from the user, eliminating the need for 2 parameters. Something like:

 string initial_UN;
 int initial_PC;

If you declare this inside your function, just before the do-while loop I suggested above, then that eliminates these 2 variables from being parameters.

Now, to get to your question, if we have the following declaration:

  Input.processInput();

Then we need to pass 4 parameters (2 if you follow my notes above) to it, and that is what the brackets next to the function name in this line of code a for. To pass a value to the function, simply, do the following (I'm only passing 2 parameters here, you can pass how many ever parameters you have defined in yout class only, not less or not more):

 Input.processInput("Username", "password");

There are 2 input parameters that specify what the username and password should be. To differentiate the parameters being passed, syntax requires a comma to split them. You can also pass variables as arguments; however, make sure that you have initialized these variables.

This is a long post, so I may have made some errors I didn't notice. If there is any other mistake I noticed, then please inform me in the comments.

Good luck!

How to call my function within parameters in my class (C++)

1 Answers1