PHP短if语句带有继续关键字并省略else部分

Question

I have a for loop like

for ($x=1; $x<=5; $x++){
    ($x == 3)? continue : true;
    //some code here
}

now on execution I am getting error

PHP Parse error: syntax error, unexpected 'continue' (T_CONTINUE) in /var/www/html/all.php on line 21

Now, this leave me with 2 questions:

1. Can I use continue key word inside short if statement?

2. For the else part of the short if, can binary values like true or false be used, and if not then how can I use short if statement if I have nothing to do for the else part.

Answer 1

continue is a statement (like for , or if ) and must appear standalone. It cannot be used as part of an expression . Partly because continue doesn't return a value , but in an expression every sub-expression must result in some value so the overall expression results in a value. That's the difference between a statement and an expression.

cond ? a : b cond ? a : b means use value a if cond is true else use value b . If a is continue , there's no value there.

true does result in a value ( true ), so yes, it can be used as part of an expression.

Answer 2

You cannot use continue inside short if-statement. Short if-statements is for returning values, like this

$val = $bool ? $one : $two;

Now, $val will have either the value of $one or the value of $two , depending of the truth value of $bool .

continue is no value, so it cannot be used in short if-statement. Use normal if-statement for this operation.

In this case, I would have done it like this:

for ($x=1; $x<=5; $x++){
    if($x == 3) continue;
    //some code here
}

Answer 3

You can use continue key word inside if statement like this; (according to PHP documentation)

<?php
 for ($i = 0; $i < 5; ++$i) {
  if ($i == 2)
      continue
  print "$i\n";
  }
?>