我如何编写带有计数器的 function？

Question

First week coding please be kind.
I need to get 4 inputs from the user and if 2 of those are -100 I need function to say you fail.

I need to implement the function here and probably add a counter inside but I dont know how.

Code looks something like this

cout << "What are the grades of your 4 take-home exams? ";
    cin >>th1>>th2>>th3>>th4;
function here

Answer 1

I need to get 4 inputs from the user

cin >>th1>>th2>>th3>>th4;

Looks like this is correct.

if 2 of those are -100

1. Conditionals

The answer is in your question itself. Focus on the word if .

Programming languages have all sorts of different ways to check things, to check if something is equal to something else, or if something is less than something else, run a certain piece of code. We call these conditions . If a certain condition is true , do something, else , do something different. Example:

int x = 0;
cin >> x; // take input from user
if (x > 20)
{
   cout << "x is greater than 20";
}
else 
{
   cout << "x is less than 20";
}

Moreover, You can even check two variables at the same time!!

int x = 1;
int y = 2;
if (x == 1 && y == 2)
   cout << "X is 1, and y is 2";
else
   //print something else

Functions

Functions are a way to put some code in a block, that you can reuse whenever you want. Think of this like, suppose you are making a cake and you need a certain syrup for it. Now if you want, you can make that syrup every time from zero, or you can just make a lot of syrup, and use it every time when you want to make a cake. It's definitely a bad example, but you get the point.

Lets make a small function. This function will take an int as parameter and check if that parameter is equal to 100 or not. If it is equal to 100, we will return a value: 1 to the caller. Otherwise we will return a value: 0 :

int checkIfHundredOrNot(int value)
{
    if (value == 100)
       return 1;
    else
       return 0;
}

//caller
int main()
{
    int x = 0;
    cin >> x;
    int result = checkIfHundredOrNot(int value);
    cout << "Result is: " << result;
    return 0;
}

With this information, try and solve your problem. It should be fairly straightforward. If you find anything difficult, google it. You will find all your answers there. Specifically google this:

• What is a function parameter in C++?
• What is return value in C++?
• What is a function in C++?
• Why do we use functions in C++?
• What are operators in C++?
• What are comparison operators in C++?
• Is there a difference between = and == ?

Then read them carefully and write down every piece of code with your own hands and repeat till you understand it.

Answer 2

So I m kind of a noob myself but I ll give it a shot. I would recommand taking a look at my solution and try doing yours in a "you" way since there are manny more paths to achieving the right answer. If you are really specific about only having 4 inputs you can try this:

bool isFail(int a, int b, int c, int d) {

int counter = 0;
if (a == -100) {
    counter++;
}
if (b == -100) {
    counter++;
}
if (c == -100) {
    counter++;
}
if (d == -100) {
    counter++;
}

if (counter >= 2) {
    return true;
}
else
{
    return false;
}

}

The function basically takes 4 ints and checks each one of them against -100. If they turn out to be -100 the counter increases by 1. Afterwards we simply check if the counter is equal to or bigger than two and if so we return a true value since it is failed (tow or more inputs are -100). If not, we simply return a false.

In your main function you can simply initialize your variables, input them and simply do a function call that you can compare against another "true" value. If the result is positive you print out a fail message.

int a, b, c, d;
std::cin >> a >> b >> c >> d;

if (isFail(a, b, c, d) == true) {
    std::cout << "Fail!" << std::endl;;
}
else
{
    std::cout << "Passed!" << std::endl;
}

Best regards!