Question

A program contains the following function int cube (int num) \\{ return num \(\star\) num \(\star\) num; \\} Write a statement that passes the value 4 to this function and assigns its return value to the variable result.

Short answer

Answer: First, declare a variable named 'result'. Then, call the 'cube' function with an argument of 4 and assign the return value to the 'result' variable like this: result = cube(4);

Step-by-step solution

Declare a variable 'result' to store the return value

Declare a variable with the datatype of the return value (int) and name it 'result'.

Call the 'cube' function with an argument of 4 and assign the return value to 'result'

To pass the value 4 to the function and assign the return value to the declared variable, write the following statement: result = cube(4);

Key concepts

Function Declaration in C++

In C++, a function declaration provides information about the function's name, return type, and parameters it can take. It sets up the structure so the compiler knows how to handle the function when called later in the code. When you declare a function, it generally follows this syntax:

• Return type: This specifies what data type the function will return, such as int, double, or void.
• Function name: It is the identifier selected for the function.
• Parameter list: In brackets, it declares what parameters the function takes. For example, int num indicates that it takes a single integer.

For instance, in the function:
int cube (int num)
The return type is int, the function name is cube, and it takes one integer parameter named num. This sets up the function to be defined and used later in the program.

Understanding Function Arguments

Function arguments are the actual values you pass into the function's parameters when you call it. Consider them as inputs the function uses to perform operations. When you pass data as an argument, you need to ensure the type matches the function's parameter type. If a function is declared to take an integer, only an integer should be passed.

When calling the function cube like this:
cube(4), you're passing the integer 4 as an argument. During this call, the value 4 is assigned to the function's parameter num. The function then uses this value within its block to perform calculations, returning the outcome of those operations back to wherever the function was called.

Return Values in C++ Functions

A return value in a C++ function is the function's result, which is sent back to where the function was called. It completes the function's execution and outputs data based on the operations performed within the function. Return values are essential for functions designed to compute and provide results that can be used later in the program.

In our example, the cube function returns an integer value calculated by multiplying the parameter num three times. It uses the return statement to send this calculated value back. So when the statement result = cube(4) is executed, the cube function calculates the cube of 4, returns 64 as the computed result, and assigns it to the variable result.