basic php array from loop

Question

im trying to create an array from a loop in PHP.

I want the array to end up something like $array(100,100,100,100), this is my code:

$x = 0; 
while($x < 5){ 
$array[$x] = 100; 
$x++; 
} 

echo $array[0];

It outputs 1 instead of 100. Can someone tell me where i'm going wrong.

For me, copy/pasted straight into the PHP interpreter it works correctly. PHP 5.3.8 — Michael Berkowski
– Michael Berkowski, Commented Oct 22, 2011 at 22:45
Works like a charm for me: codepad.org/9U8Yfqfp. Are you sure that the $array is empty before inserting the new values? — Marcus
– Marcus, Commented Oct 22, 2011 at 22:46
A for loop would be more appropriate than while here for ($x = 0; $x < 5; $x++) since you know both the starting and ending values of $x. i.e. since you have a predetermined number of iterations. — Michael Berkowski
– Michael Berkowski, Commented Oct 22, 2011 at 22:46

user142162 · Accepted Answer · 2011-10-22 22:45:37Z

5

Even though it works perfectly for me, you should be initialising the variable beforehand.

$array = array();

For example, if $array is non-empty string, you will see the output of 1.

answered Oct 22, 2011 at 22:45

user142162

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3 Comments

NikiC Over a year ago

could you explain why it happens with the non empty string? I could imagine that it results in 11111 by casting 100 to string and taking the first char, but can't imagine why it is 1.

Jared Farrish Over a year ago

@NikiC - It's because it's setting a character in the string, and not a new array value, and $array[0] will be the first "character" in the string; see my second demo.

NikiC Over a year ago

ah, got it, $array[0] is output, so it takes only the first 1.

NikiC · Accepted Answer · 2011-10-22 22:48:08Z

3

You can just use the predefined array_fill function for that:

$array = array_fill(0, 5, 100);

answered Oct 22, 2011 at 22:48

NikiC

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Comments

orangething · Accepted Answer · 2011-10-22 22:54:15Z

2

The other answers pretty much cover this. I would, however, recommend you use a for loop for this instead of a while loop if you're going to use a loop rather than a function to do it.

$array = array();
for($x=0; $x<5; $x++) {
    $array[$x] = 100;
}

In fact, you could make this even shorter.

$array = array();
for($x=0; $x<5; $array[$x++]=100);

It's perfectly valid to have a for loop statement instead of a block. And blocks can go anywhere too; they don't need an if statement, for loop, while loop, or whatever, before them.

answered Oct 22, 2011 at 22:54

orangething

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