for loop works in js style, but recommended?

lajkonik86

I've been learning some JS lately, and some coding styles are mixing around. Is there anything wrong with doing:

for($x=0;@$config[$x];$x++) {

}

in php?

halojoy

the syntax of for loop in PHP is described here, with examples
[man]for[/man]
http://php.net/for
Basically:

// for( $i=number start value; condition for to go on; $i++ increases $i ){
// do something
}

$count = 5;
for( $i=1; $i<=$count; $i++ ){
    echo $i. '-';
}
// will print: 1-2-3-4-5-

NogDog

There's nothing technically wrong with that syntax, but if the objective is to loop through the $config array, using a foreach loop is a bit cleaner:

foreach($config as $ix => $value)
{
   echo "The value of \$config[$ix] is '$value'<br />\n";
}

(The $ix => is optional, and is only needed if you need access to the current array index within the loop.)

lajkonik86

well in my case i had an array like this

1 => 'red'
0 => 'green'

but i needed to go through it in the order of 0 first and then 1, foreach does it the other way around.

the javascript style for loop surprised me, was always very used to my foreach 🙂

In the end i decided to just use a database sort, so that my array comes out like

0 => 'green'
1 => 'red'

Suppose i could have also done a ksort on the array
my code in example one couldn't work because it was possible to have 1 and then 3, so skipping the two

bradgrafelman

lajkonik86 wrote:
my code in example one couldn't work because it was possible to have 1 and then 3, so skipping the two

Precisely why using a for() loop to iterate through an array can have drastic effects unless you know for certain the structure of the array.

If you really wanted a $i counter as well as looping through each item in an array, you could use a for() loop in the way that a foreach() does:

for($keys=array_keys($array),$i=0; isset($keys[$i]; $i++) {
    echo 'Item number ' . ($i+1) . ': ' . $array[ $keys[$i] ] . '<br>';
}

Weedpacket

lajkonik86 wrote:
but i needed to go through it in the order of 0 first and then 1, foreach does it the other way around.

Do you mean you needed to [man]ksort[/man] the array first?

Incidentally, the original loop will stop as soon as it encounters a value that is equivalent to false - whether it's the last element of the array or not.

$array = array('a','b','0', 'c');
for($i=0; @$array[$i]; $i++)
{
	echo $array[$i];
}

And using the error-suppression '@' operator tends to be a performance hit.