Functions Reference Sheet

Most larger C++ programs are written as a collection of smaller sections, called functions. Each function performs a specific task and can return a value such as a number or a string.

Every program has at least one function, the main function. Additional functions may be used in the main function or some other function, either as a command or as part of a math formula.

To create a function, two pieces of code must be added to the C++ program:

• The function prototype, a line that gives the function’s name and data type, along with a list of parameters.
• The function definition, which begins with a line exactly like the prototype (except without a closing semi-colon), and then has a set of { } braces containing the function’s C++ code, known as the body of the function. The body should include a return statement that sends back the result of the function (typically this is the last line of the body).

Framework of a C++ program with functions

// Your name
// Date
// Assignment

#include <iostream.h>		// Needed to use cout and cin
#include <math.h>  		// Needed to use math functions like ceil
#include "apstring.h"   // Needed to use the apstring type.

float funcname (int x, float y);  // Function prototypes go here. This is an example.

int main()
{
	Here you can declare variables for the main program...

	Commands go here...

	return 0;
}

float funcname (int x, float y)		// Function definitions go here. This is an example.
{
	Here you can declare "local" variables to be used only inside this function...

	Commands go here...

	return valuetoreturn;
}