How does this for loop work?


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I was wondering if someone could help me understand what's happening here:

Code:
    int set = 0;
    for (auto & info : m_guidancePlugin->jobGuidanceList())
    {
      set |= info.type;
    }

Mainly this part:

Code:
set |= info.type
 
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IT's hard to say without knowing what info.type is, or auto is... or m_guidancePlugin for that matter...

But that line is a binary "or". So whatever info.type is it's likely some sort of use of binary flags.

For example you might have something like:
Code:
#define ALLOW_NONE  0x00
#define ALLOW_READ  0x01
#define ALLOW_WRITE 0x02
#define ALLOW_EXEC  0x04

Let's say you want users permissions to set the file permissions.

Code:
int permission = user.isLoggedIn ? ALLOW_READ | ALLOW_NONE;
if (user.isModerator) permission |= ALLOW_WRITE;
if (user.isAdmin) permission |= ALLOW_EXEC | ALLOW_WRITE;

If they're logged in it's at least 1, if they're a moderator it's 3, if they're an admin, it's 7.

Since 0x01 | 0x02 | 0x04 == 0x07

Just as ALLOW_READ | ALLOW_EXEC is 5.

Most C operators can be used on assignment. *=, /=, +=, -=, |=, &=, even ~= is valid. In this case it's the same as saying:

set = set | info.type
 
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IT's hard to say without knowing what info.type is, or auto is... or m_guidancePlugin for that matter...

I think it would take a lot of time and code to explain all of that, but here is the definition for type:

Code:
Guidance::Type type = Guidance::StraightAB;

where Guidance::StraightAB = 2 and type is 4 bytes.
 

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