Functions in C++

Functions in C++

Functions in C++ are the same as functions in C. Functions are artifacts that enable you to divide the content of your application into functional units that can be invoked in a sequence of your choosing. A function, when called (that is, invoked), typically returns a value to the calling function. The most famous function is, of course, main(). It is recognized by the compiler as the starting point of your C++ application and has to return an int (i.e., an integer). 

You as aprogrammer have the choice and usually the need to compose your own functions. Example 1.1 is a simple application that uses a function to display statements on the screen using std::cout with various parameters.

Example 1.1. Declaring, Defining,and Calling a Function That Demonstrates Some Capabilities of std::cout

1: #include <iostream>

2: using namespace std;

3:

4: // Function declaration

5: int DemoConsoleOutput();

6:

7: int main()

8: {

9: // Call i.e. invoke the function

10: DemoConsoleOutput();

11:

12: return 0;

13: }

14:

15: // Function definition

16: int DemoConsoleOutput()

17: {

18: cout << “This is a simple string literal” << endl;

19: cout << “Writing number five: “ << 5 << endl;

20: cout << “Performing division 10 / 5 = “ << 10 / 5 << endl;

21: cout << “Pi when approximated is 22 / 7 = “ << 22 / 7 << endl;

22: cout << “Pi more accurately is 22 / 7 = “ << 22.0 / 7 << endl;

23:

24: return 0;

25: }

Output:

This is a simple string literal

Writing number five: 5

Performing division 10 / 5 = 2

Pi when approximated is 22 / 7 = 3

Pi more accurately is 22 / 7 = 3.14286