If void() does not return a value, why do we use i

Question

void f() means that f returns nothing. If void returns nothing, then why we use it? What is the main purpose of void?

Answer 1

probably to tell the compiler " you dont need to push and pop all cpu-registers!"

Answer 2

Cause consider some situations where you may have to do some calculation on global variables and put results in global variable or you want to print something depending on arguments , etc.. In these situations you can use the method which dont return value.. i.e.. void

Answer 3

Because sometimes you dont need a return value. That's why we use it.

Answer 4

Here's an example function:

struct SVeryBigStruct
{
    // a lot of data here
};

SVeryBigStruct foo()
{
    SVeryBigStruct bar;
    // calculate something here

    return bar;
}

And now here's another function:

void foo2(SVeryBigStruct& bar) // or SVeryBigStruct* pBar
{
    bar.member1 = ...
    bar.member2 = ...
}

The second function is faster, it doesn't have to copy whole struct.

Answer 5

If you didn't have void, how would you tell the compiler that a function doesn't return a value?

Answer 6

Sometimes it can be used to print something, rather than to return it. See http://en.wikipedia.org/wiki/Mutator_method#C_example for examples