Predefined Functions

C++ comes with libraries of predefined functions. The predefined functions are found in libraries. To make the functions available, the library must be included in a program.  A include directive tells the compiler which library header file to include.

A Function Calls tell the name of the functions to use.  Can be use like any expression.  Is used in a statement where the returned value makes sense. For example:

side = sqrt(area);
To include the math library containing sqrt(); we use #include <cmath>

Other Predefined Functions are:

A Type Cast produces a value of one type from another type.  For example: static_cast<double>(total_candy) produces a double representing the integer value of total_candy.

A Function definition describe how the function does its task.  Can appear before or after the function is called.

//code to make the function work

A Function declaration show how the function is called.  Must appear in the code before the function is called.  Tell the return type name of function.

Function_name(Parameter_list);

The Return Statement ends the function call and returns the value calculated by the function.

return expression;

• expression performs the calculation or expression is a variable containing the calculated value.  For example:
• return subtotal + subtotal * TAX_RATE;

A Pseudocode is a mixture of C++ & English.  They simplifies algorithm design by allowing you to ignore the specific syntax of the programming language as you work out the details of the algorithm.

Global variable: rarely used when move than one function must use a common variable.