Question

Examine the following function header, then write an example call to the function. void showValue(int quantity)

Short answer

Answer: To call the function, you would write `showValue(5);`

Step-by-step solution

Understanding the Function Header

The given function header is "void showValue(int quantity)". This means that the function is named "showValue" and takes a single integer parameter named "quantity". The function has a return type of "void", meaning that it does not return any value.

Writing an Example Function Call

To call the "showValue" function, we need to pass a single integer value as an argument. Let's provide the value 5 as an example. The example function call should look like this: ```cpp showValue(5); ```

Key concepts

Function Header in C++

The backbone of a C++ function is its header, which details the function's name, return type, and parameters, providing a blueprint for its usage. The header is a critical component, appearing at the beginning of a function definition. For instance, in the function header void showValue(int quantity), we identify three key elements: 'showValue' is the function's name, indicative of the action or operation it performs; 'void' specifies that the function returns no value; and '(int quantity)' declares a single parameter, meaning this function expects one integer value to be supplied when it is called.

Understanding a function header is essential as it dictates how the function is to be used. A function call must align with the header's specifications. If the header defines one integer parameter, the function call must provide an integer argument; no more, no less. Similarly, if the header indicates a 'void' return type, the caller should not expect any data returned from the invocation of the function.

Void Return Type

In C++, the 'void' return type is used to declare that a function does not return a value. When you see void before a function's name, it tells you that after performing the operations within the function, it will simply finish without providing any output to the caller. This contrasts with other functions that return data, such as an integer or a float, where the return type would instead specify the type of value to expect.

Using the 'void' return type can be particularly useful for functions that perform actions such as printing to the console, manipulating global variables, or simply acting as a sequence of instructions without the need to report back. In the original exercise, showValue(int quantity) is such a function. It likely performs a task, like displaying the value of 'quantity' to the user, without needing to send any value back to the function's point of call.

Integer Parameters

Parameters in C++ functions act as placeholders for values that are passed into the function when it is called. They are essential for a function's flexibility, allowing it to operate on different values without changing the function's code. An 'integer parameter', as suggested by its name, expects an integer value when the function is called.

For example, int quantity in the function header void showValue(int quantity) from our original exercise declares that it requires an integer argument. Parameters like this allow functions to be versatile and reusable, because the same function can operate with different integer values over different calls. To successfully call the function, as seen in step two of the solution, the integer value 5 is passed to showValue as an argument: showValue(5). This integer parameter makes showValue operate on the integer value 5 during this specific call, but it is free to accept any integer value in subsequent calls.