Question

Consider the following function definition: int func (int \(x,\) double \(y,\) char \(u,\) string name) 1 / / function body \\} Which of the following are correct function prototypes of the function func? a. int func \((x, y, u,\) name) b. int func (int \(s\), double \(k\), char ch, string name); c. int func (int, double, char, string) d. func (int, double, char, string)

Short answer

Correct function prototypes: b and c.

Step-by-step solution

Identify Correct Syntax for Function Prototypes

A function prototype must include the return type, the function name, and the types of all parameters. It can include the names of the parameters, but these are optional.

Assess Option A

Option a lacks types for each parameter, which is a mandatory part of function prototypes: `int func(x, y, u, name)` is incorrect because it does not specify the types of parameters.

Assess Option B

Option b `int func (int s, double k, char ch, string name);` provides return type, parameter types, and optional names; it matches valid prototype format.

Assess Option C

Option c `int func (int, double, char, string)` includes return type and parameter types without naming the parameters, which is still a correct prototype syntax.

Assess Option D

Option d does not specify a return type, making it an incorrect prototype. The format `func (int, double, char, string)` lacks the return type at the start.

Key concepts

Return Type

The return type is fundamental in defining a function in C++. It tells the compiler what type of value a function will return when it completes execution. For example, in the function `int func(...)`, the `int` keyword at the beginning signifies that the function will return an integer value.
Knowing the return type is crucial for both writing and understanding code, as it helps predict the function's output.

• If a function returns no value, the `void` keyword is used.
• Common return types include `int`, `double`, `float`, `char`, and custom types using classes or structures.

The function's return type must match the actual data type of the value returned using the `return` statement within the function body.

Parameter Types

Parameters in a function allow you to pass inputs into the function to work with. Defining parameter types is critical as it sets the expectations for the kind of data the function will process, ensuring the program operates correctly.
In the case of a function like `int func(int x, double y, char u, string name)`, each parameter's type is specified:

• `int` for `x`, signifying that `x` must be an integer.
• `double` for `y`, indicating floating-point expected input.
• `char` for `u`, suggesting a single character input.
• `string` for `name`, expecting a sequence of characters.

Understanding parameter types helps in avoiding errors. Type mismatch during function calls can lead to compilation errors or undefined behavior in the program.

C++ Function Syntax

The structure of a function in C++ is specific and consists of several components. Here's a brief overview of how a function is declared:
- **Return Type:** As discussed earlier, the type of value the function returns. - **Function Name:** This is the identifier by which you call the function. - **Parameter List:** Enclosed in parentheses, detailing the data types and, optionally, the names of inputs. An example function header looks like `int func(int x, double y, char u, string name)`. This denotes a function named `func` which takes four parameters, each with a clearly defined type.
The syntax rules ensure that the compiler understands how to handle the function. Adhering to proper C++ function syntax is essential for creating correct and functioning programs.

Function Prototype Syntax

The function prototype in C++ acts as a declaration of the function. It tells the compiler about the function name, return type, and parameter types without giving its complete body. This is especially useful when organizing code or sharing functions across multiple files.
A prototypical structure would be `int func(int, double, char, string);`. This tells us:

• The function returns an integer.
• It expects four inputs of types `int`, `double`, `char`, and `string` respectively.

Parameter names are optional in prototypes but can aid readability. The requirement for function prototypes ensures the compiler can check calls to the function against the expected types, improving code safety and reducing bugs.