Question

Write the definition of a function that takes as input three numbers and returns the sum of the first two numbers multiplied by the third number. (Assume that the three numbers are of type double.)

Short answer

Define a function with three double parameters returning (num1 + num2) * num3.

Step-by-step solution

Understanding the Problem

The exercise requires defining a function that takes three numbers as input. These numbers are of type 'double', which is a data type used to represent decimal numbers.

Formulating the Function Signature

In programming, a function signature includes the name of the function, its parameters, and its return type. Here, the function should return a 'double' and accept three 'double' parameters.

Breaking Down the Operations

The function needs to compute the sum of the first two numbers and then multiply this sum by the third number. So, if the numbers are a, b, and c, the operation we want is (a + b) * c.

Writing the Function Code

Using the previously determined operations, the function can be written as: ```cpp #include using namespace std; double calculate(double num1, double num2, double num3) { return (num1 + num2) * num3; } int main() { cout << calculate(2.0, 3.0, 5.0); // Example usage return 0; } ``` This code defines and tests the function 'calculate', which implements the requested operations.

Key concepts

Function Definition in C++

A function in C++ is a block of code designed to perform a specific task. Defining a function involves specifying what it does and how it will be called. When you define a function, you'll outline its name, followed by parameters it needs to operate, and the type of value it will return. Most often, a function definition consists of the following parts:

• Return Type: Indicates what type of data the function will return.
• Function Name: A unique identifier that differentiates the function from others.
• Parameters: These are input values that the function uses to generate output.
• Function Body: Contains the code that defines what the function does.

In our exercise, the function is defined to calculate a certain value using three numbers passed to it as parameters.

Understanding Function Parameters

Function parameters are values passed to a function to be used within its operations. They serve as placeholders for the actual values you provide when calling the function.
In the C++ function `calculate`, three parameters are used:

• num1: Represents the first number to be added.
• num2: Represents the second number to be added.
• num3: Used to multiply the sum of `num1` and `num2`.

Function parameters allow your function to be flexible, enabling it to operate on different values. These parameters must match the types expected by the function, ensuring that the operations within the function can be completed without errors.

Exploring the Return Type

The return type of a function specifies the type of value that the function will output once it has completed its task. It is declared prior to the function name in the function definition.
In this exercise, the return type is `double`, meaning that after performing the necessary calculations, the function outputs a double precision floating-point number.
Choosing the correct return type is crucial as it impacts how you can use the function’s result in your program later. Not only does it guarantee that the return value is appropriate for its intended use, but it also helps in managing how this value can interact with other parts of your code.

The Importance of the Double Data Type

The `double` data type in C++, short for double precision floating-point, is used to represent numbers with decimal points with larger ranges and precision compared to the `float` data type.

• Double is typically allocated 64 bits in memory, offering improved precision.
• Commonly used for mathematical calculations requiring a high level of accuracy.

In our exercise, using `double` is crucial for calculations involving decimal numbers to ensure that the results are as precise as possible.
By utilizing the `double` data type, computations involving sums and multiplications of numbers with decimal points are both accurate and reliable, avoiding potential precision loss associated with narrower data types.