What does the vertical bar ( | ) mean in C++?

Question

I have this C++ code in one of my programming books:

WNDCLASSEX wndClass = { 0 };
wndClass.cbSize = sizeof(WNDCLASSEX);
wndClass.style =  CS_HREDRAW | CS_VREDRAW;

What does the single pipe do in C++ windows programming?

This has nothing to do with windows programming; this is a basic operator of C++. — Nicol Bolas, Apr 15 '12 at 16:58

Zeta · Accepted Answer · 2012-04-15T17:03:45.147

34

Bitwise OR operator. It will set all bits true that are true in either of both values provided.

For example CS_HREDRAW could be 1 and CS_VREDRAW could be 2. Then it's very simple to check if they are set by using the bitwise AND operator &:

#define CS_HREDRAW 1
#define CS_VREDRAW 2
#define CS_ANOTHERSTYLE 4

unsigned int style = CS_HREDRAW | CS_VREDRAW;
if(style & CS_HREDRAW){
    /* CS_HREDRAW set */
}

if(style & CS_VREDRAW){
    /* CS_VREDRAW set */
}

if(style & CS_ANOTHERSTYLE){
    /* CS_ANOTHERSTYLE set */
}

See also:

edited Apr 15 '12 at 17:03

answered Apr 15 '12 at 16:58

Zeta

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whaa..? all bits to true? so let me think. 010101 | 101010 would return 111111? – quakkels Apr 15 '12 at 17:01
6

Yes. `b00010101 | b00101010` will return `b00111111`. – Zeta Apr 15 '12 at 17:04

score 11 · Answer 2 · answered Apr 15 '12 at 16:57

11

| is called bitwise OR operator.

|| is called logical OR operator.

answered Apr 15 '12 at 16:57

Nawaz

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score 8 · Answer 3 · answered May 20 '22 at 06:46

8

In C++20, it can also be the pipe operator of range adaptor closure objects. I.e. chaining together operations on ranges. Read more about it here: https://en.cppreference.com/w/cpp/ranges#Range_adaptor_closure_objects

answered May 20 '22 at 06:46

Iizuki

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https://github.com/ReactiveX/RxCpp check it out – Yomi1984 Apr 13 '23 at 11:58

score 5 · Answer 4 · answered Apr 15 '12 at 16:58

5

It's a bitwise OR operator. For instance,

if( 1 | 2 == 3) {
    std::cout << "Woohoo!" << std::endl;
}

will print Woohoo!.

answered Apr 15 '12 at 16:58

Michael Foukarakis

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What does the vertical bar ( | ) mean in C++?

4 Answers4

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