Function calling in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a function call in C++?

A function call is when you ask a function to run its code by using its name followed by parentheses, optionally with arguments inside.

beginner

How do you pass information to a function when calling it?

You pass information by putting values called arguments inside the parentheses of the function call.

beginner

What happens if a function returns a value?

When a function returns a value, the function call can be used in expressions or assigned to variables to use that returned value.

beginner

Example: What does this code do?<br>

int add(int a, int b) { return a + b; }<br>int result = add(3, 4);

It calls the function 'add' with 3 and 4 as arguments. The function adds them and returns 7, which is stored in 'result'.

intermediate

Can a function call be inside another function call?

Yes! This is called nesting. For example, you can call a function inside the arguments of another function call.

What is the correct way to call a function named 'printMessage' with no arguments?

A call printMessage();

B printMessage;

C printMessage();

D printMessage[];

In C++, to call a function you use its name followed by parentheses. If there are no arguments, the parentheses are empty.

If a function 'sum' takes two integers, how do you call it with 5 and 10?

A sum{5, 10};

B sum[5, 10];

C sum 5, 10;

D sum(5, 10);

Function arguments are passed inside parentheses separated by commas.

What does this function call return?<br>

int square(int x) { return x * x; }<br>square(3);

A 9

B 6

C 3

D 0

The function multiplies 3 by 3 and returns 9.

Which of these is a nested function call?

A sum(2, 3);

B print(sum(2, 3));

C print(); sum(2, 3);

D sum(2, 3); print();

Calling 'sum' inside the arguments of 'print' is nesting function calls.

What happens if you forget the parentheses when calling a function?

A The function does not run; it refers to the function itself.

B The function runs anyway.

C It causes a syntax error.

D The program crashes immediately.

Without parentheses, you refer to the function, not call it.

Explain in your own words what happens when you call a function in C++.

Think about how you ask a friend to do something by name.

Describe how you can use the value returned by a function call.

Returned values are like results you can use immediately.