How to limit maximum length of PHP array?

Question

I create an output file called `$output` which is a number of text lines with line breaks. These lines are created on a webpage for which I then use **cURL** to get the contents which are the essentially lines of text with line breaks.

I then create an array as follows:

```
$arrayoutput = explode("
", $output);
```

This works quite good until the `$output` file becomes so large I get the following error:

```
Allowed memory size of 134217728 bytes exhausted (tried to allocate 32 bytes) ---> 128M
```

The `$output` file is not always that big, but on occasion can be.

Now I do not want to increase memory levels or anything like that. I would like to be able to limit the maximimum length of the array.

Let's say, create the array with only, 100,000 lines maximum in it, or whatever to be within memory limits. When it reaches 100,000 elements, it stops.

Is it possible to do this?

spork · Accepted Answer

Don't use `explode()`, instead write a function to produce the array by iteratively regex-matching a line and adding it to the array, stopping if you've reached max size. For example:

```php
$arrayLimit = 100000;
$arrayoutput = [];

$separator = "
";
$line = strtok($output, $separator);

while ($line !== false && count($arrayoutput) < $arrayLimit) {
    $arrayoutput[] = $line;
    $line = strtok($separator);
}

// $arrayoutput will contain 100000 elements or less

```

See [strtok](https://www.php.net/strtok). Note: only the first call to strtok uses the string argument. Every subsequent call to strtok only needs the token to use, as it keeps track of where it is in the current string.

I believe you could also do this with `preg_split` and avoid memory issues:

```php
$arrayLimit = 100000;
$arrayoutput = [];

foreach(preg_split("/((?
)|(
?))/", $output) as $line){
    $arrayoutput[] = $line;

if(count($arrayoutput) >= $arrayLimit) {
        break;
    }    
}

// $arrayoutput will contain 100000 elements or less
```

With the second example you also have an easier way to match output that has different line endings as that typically varies between Linux, Windows, and Mac.

wpas

2 Answers

spork

devilwood

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