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php local file reading shenanigans

LOUOS
By LOUOS
in Programming
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Posted

Hi, so for the last three hours I have been trawlling through youtube videos and forums trying to find out a way of reading a .txt file and storing it as a javascript variable. Initially I was hoping for something similar to pythons .open and .read procedure in javascript. However what I found out was that you have to do that in php then "send it" to the javascript so this is what I've come up with:

  


<!DOCTYPE html>
<html>
<body>
<script>
function Number(){
    var x = "<?php echo $myfile;?>";
    alert(x);
}
window.addEventListener('load',Number);
</script>
<?php 
$rawfile = fopen("obstacles.txt", "r");                  // obstacles contains 'I hate php'
$myfile = fread($rawfile,filesize("obstacles.txt"));
?>

</body>
</html>

 

The alert always just contains <?php echo $myfile;?> as text (I hesitate to say string). Would appreciate help with problem. :)

 

PS. If theres anything about opening directly as an array that would be great.

temporary solution - someone else's problem

 

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Posted

You'll have to do the file reading before the html code, otherwise the variable $myfile will be empty when the html code is sent to the output buffer.

 

You also have functions like file_get_contents($filename) which read a whole file and return a string that has the whole contents of the file (no need for multiple calls)

 

Also you should close the file handle using fclose($rawfile) if you want to be nice (though php would kill the handle as soon as the script finishes. It's just good to make it a habit to not leave things open

 

later edit:  if you don't want code at the top and you don't want to use file_get_contents you can do something like this

  

<!DOCTYPE html>
<html>
<body>
<script>
function Number(){
    var x = "<?php echo my_custom_function_name();?>";
    alert(x);
}
window.addEventListener('load',Number);
</script>
<?php 
  
function my_custom_function_name() {  
	$rawfile = fopen("obstacles.txt", "r");
 	$fileinfo = fstat($rawfile);
	$myfile = fread($rawfile,$fileinfo['size']);
  	fclose($rawfile);
  	return $myfile;
}
  
?>

</body>
</html>

 

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Posted (edited)
  • Author

this better? 

<!DOCTYPE html>
<html>
<body>
<?php 
$myfile = file_get_contents("obstacles.txt");
?>
<script>
function Number(){
    var x = "<?php echo $myfile;?>";
    alert(x);
}
window.addEventListener('load',Number);
</script>
</body>
</html>
Edited by LOUOS

temporary solution - someone else's problem

 

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Posted

No need to use fopen if you use file_get_contents  , file_get_contents does everything (opens file, reads everything , closes file, returns content or empty string if file is not found or error reading it).

 

Read documentation : http://docs.php.net/manual/en/function.file-get-contents.php

 

later edit: also keep in mind that fread doesn't guarantee that it will always read as much as you tell it. In some rare cases, the fread function may return a smaller amount than what you want or even 0 bytes, even if the file is bigger or there's still bytes left to read. It depends on operating system and other things. 

So the parameter size is just a "hint", a suggestion. For reading huge files, you should read chunks at a time (for example 64 KB pieces) and stop when both fread returns 0 bytes AND feof() function says you reached the end of file.

For example, if the text file is as big as 1 MB , the operating system or php may only read 64KB or 512 KB in one shot and will only return that much.

If you use fread to read a file, you would use a while not end of file  .. read chunk , add chunk to a string, read next chunk etc

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Posted

You should not be using PHP to output a value into a Javascript variable like that.

 

If your Javascript requires a value from the server then you need to do an XMLHttpRequest (ajax) request to your PHP script which will return the required data in a data format that can be interpolated by Javascript most commonly used would be JSON.

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