PHP assignment with a default value

问题

What's a nicer way to do the following, that doesn't call f() twice?

$x = f() ? f() : 'default';

回答1:

In PHP 5.3, you can also do:

  $a = f() ?: 'default';

See the manual on ?: operator.

回答2:

This seems to work fine:

$x = f() or $x = 'default';

回答3:

function f()
{
  // conditions 
  return $if_something ? $if_something : 'default';
}

$x = f();

回答4:

$x = ($result = foo()) ? $result : 'default';

test

回答5:

You could save it to a variable. Testcase:

function test() {
        echo 'here';
        return 1;
}

$t = test();
$x = $t ? $t : 0;
echo $x;

来源：https://stackoverflow.com/questions/4832114/php-assignment-with-a-default-value