Вивчайте Void Data Type | Other Data Types and Concepts

You always have to specify the type because it is a statically-typed language. The compiler needs to know the exact type of each variable to allocate the correct amount of memory and to enforce type safety. It also needs to know the types of function return values and parameters.

Note

A statically-typed language is one where the data type of a variable is explicitly declared and enforced by the compiler.

main.cpp


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#include <iostream>

// Let's consider a simple example.
// Imagine you need to create a function that logs something in console.
// What type should it return?
___ log(std::string message)
{
    std::cout << message;
    return ___;
}

In this case, we don't require a specific return type it could be int, double, float, or bool. For this scenario, the exact type doesn’t matter. In fact, what if we don’t need to return anything at all?

Void as a Function Return Type

There are often functions that seems to not need to return anything like:

main.cpp


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// Outputting information in console
___ log(std::string message) { std::cout << message; }

// Updating values of variables
___ update(int& variable, int new_value) { variable = new_value; }

// Calling another function
___ closeFile(std::fstream& file) { file.close(); }

In this case we can use void data type. The void data type in programming signifies the absence of any value or type. It can be used in many different ways but for the function it is usually used to indicate that a function does not return any value.

main.cpp


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#include <iostream>

void log(std::string message)
{
    std::cout << message;
    return;
}

int main()
{
    log("This is a void function!");
}

Note

We used the return keyword but did not actually pass any value. The return keyword could also be omitted in void functions. Try erasing it in the example.

Void as a Pointer

Void pointers (void*) are pointers that do not have a specific data type associated with them. They can point to any type of object, but you must cast them to the appropriate type before using them. They are really useful but sometimes hard to understand.

main.cpp


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#include <iostream>
int main()
{
    int num = 10;
    // Here we are creating a void pointer
    // Now it can point to any variable of any data type
    // You can try changing the type of `num` from `int` to `float`
	void* ptr = &num;

    // To use this pointer, we need to cast it to the appropriate type
    //                        VVV
    int* intPtr = static_cast<int*>(ptr);
    std::cout << *intPtr << std::endl;  // Output: 10
}

In this example, ptr is a void pointer that points to an integer (num). We then cast ptr to an int* pointer to access and print the value of num.

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Секція 4. Розділ 3

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Suggested prompts:

What are some common use cases for void functions?

Can you explain more about void pointers and how they are used?

Why would I use a void pointer instead of a regular pointer?

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Note

A statically-typed language is one where the data type of a variable is explicitly declared and enforced by the compiler.

main.cpp


              12345678910
            
#include <iostream>

// Let's consider a simple example.
// Imagine you need to create a function that logs something in console.
// What type should it return?
___ log(std::string message)
{
    std::cout << message;
    return ___;
}

Void as a Function Return Type

There are often functions that seems to not need to return anything like:

main.cpp


              12345678
            
// Outputting information in console
___ log(std::string message) { std::cout << message; }

// Updating values of variables
___ update(int& variable, int new_value) { variable = new_value; }

// Calling another function
___ closeFile(std::fstream& file) { file.close(); }

main.cpp


              123456789101112
            
#include <iostream>

void log(std::string message)
{
    std::cout << message;
    return;
}

int main()
{
    log("This is a void function!");
}

Note

We used the return keyword but did not actually pass any value. The return keyword could also be omitted in void functions. Try erasing it in the example.

Void as a Pointer

main.cpp


              1234567891011121314
            
#include <iostream>
int main()
{
    int num = 10;
    // Here we are creating a void pointer
    // Now it can point to any variable of any data type
    // You can try changing the type of `num` from `int` to `float`
	void* ptr = &num;

    // To use this pointer, we need to cast it to the appropriate type
    //                        VVV
    int* intPtr = static_cast<int*>(ptr);
    std::cout << *intPtr << std::endl;  // Output: 10
}

In this example, ptr is a void pointer that points to an integer (num). We then cast ptr to an int* pointer to access and print the value of num.

Все було зрозуміло?

Дякуємо за ваш відгук!

Секція 4. Розділ 3

Void Data Type

Void as a Function Return Type

Void as a Pointer

Awesome!

Void Data Type

Void as a Function Return Type

Void as a Pointer