What is the difference between the | and || operators?

Question

| and || - what is the difference between these two operators in PHP?

Answer 1

Just like the & and && operator, the double Operator is a "short-circuit" operator.

For example:

if(condition1 || condition2 || condition3) If condition1 is true, condition 2 and 3 will NOT be checked.

if(condition1 | condition2 | condition3) This will check conditions 2 and 3, even if 1 is already true. As your conditions can be quite expensive functions, you can get a good

performance boost by using them.

There is one big caveat, NullReferences or similar problems. For example:

if(class != null && class.someVar < 20) If class is null, the if-statement will stop after "class != null" is false. If you only use &, it will try to check class.someVar and you get a

nice NullReferenceException. With the Or-Operator that may not be that much of a trap as it's unlikely that you trigger something bad,

but it's something to keep in mind.

No one ever uses the single & or | operators though, unless you have a design where each condition is a function that HAS the be

executed. Sounds like a design smell, but sometimes (rarely) it's a clean way to do stuff. The & operator does "run these 3 functions,

and if one of them returns false, execute the else block", while the | does "only run the else block if none return false" - can be useful,

but as said, often it's a design smell.