Php一条线需要在底层[复制]

Question

This question already has an answer here:

• What are the PHP operators “?” and “:” called and what do they do? 9 answers

what is the meaning of this line? Can any body help me? I have confusion on last 2 sign :'' why without this two sign browser make error? Thanks all.

isset($_POST['but'])? $_POST['but']:'';

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Answer 1

It's just another way to write if/else statement. For example:

$but = isset($_POST['but'])? $_POST['but']:'';

Would be the same as:

if(isset($_POST['but'])){
$but= $_POST['but'];
}else{
$but = '';
}