What is const void, and is it a valid return type?

const void in C++ is not a valid type and cannot be used as a return type for functions. In C++, the void type represents a type that carries no value and is typically used to indicate that a function returns no value. Since void has no concrete value, adding const before it is redundant and meaningless.

For example, if your goal is to write a function that returns no value (nor any modifiable value), you simply declare the function to return the void type. Here is a simple example:

cpp
void printMessage() {
    std::cout << "Hello, World!" << std::endl;
}

In this example, the printMessage function outputs a string and has no return value, so its return type is void. Adding const before void not only adds no additional information or functionality but also results in a compilation error, as it is not valid syntax. If you attempt to use const void as a return type, as shown below:

cpp
const void exampleFunction() {
    // Do something
}

This will cause a compilation error because const void is not a valid type declaration. In summary, the correct approach is to use void instead of const void when you want a function to return no value.