How to echo variable before declaration? php

I need to echo a var in a page but the value is declared later after being included in the page.

Is there any way to echo a var before I declare it? or some way to include the page withought running any of the code and j开发者_如何学运维ust getting the var?

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No language is obviously able to output a value, before it exists.

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If you want to do something like..

echo $var;

$var = "Hello world";

Then the answer is no. PHP is an interpreted language which runs downwards, not every which way.

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The simplest, best and most sensible option is to fix your logic so everything happens in a logical order.

Failing that. Store your data in a variable instead of outputting it. Include a placeholder where you want the variable to be. Then do a search and replace on that placeholder once you have the data you need.

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You can build a template-like solution. Put something like ##var## in the page, use ob_start() at the beginning of the page, define your $var whereever, then, at the end of the page, use echo str_replace('##var##', $var, ob_get_clean());.

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Example:

<?php ob_start() ?>
<p>##test##</p>
<?php $test = "this is a test paragraph" ?>
<?php echo str_replace("##test##", $test, ob_get_clean()) ?>

Check out ob_start(), and ob_get_clean().

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There is a way to use JavaScript with PHP for this kind of echos.

$echo  = document.getElementById('dispaly_div').innerHTML = "$variable";

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One way is to use functions.

For example:

function printvar($string) {
  echo $string;
}
      
printvar("Hello World!");

This is tested and works.