Php read first 10 lines file

It's nice to be able to generate an html table from a PHP array. I know how to
do this, but the array in question is built from a file. The file in question
can be very long, and I only want the first 10 lines. So, I'd like to reduce
the overhead it takes to read the file into the array by limiting the number of
lines read in - rather than have the entire file read in and then limiting the
output to the html table.

$visits= file("visdata.txt");
//reverse the array so table is ordered by date decending
$visits = array_reverse ($visits);
//show only the last 10 visitors
$number_of_visits = count($visits);
if ($number_of_visits > 10)
{
$number_of_visits = 10;
}
echo
"

There must be a way to limit how many lines from the file are read into the
array -- any suggestions?

Thanks in advance.

Jul 17 '05 #1

Introduction

Here you will see how to read last n lines from a file in PHP, where n could be replaced by any positive integer number, such as, 1, 2, 5, 10 etc. Generally most of the times you may use to read the file in forward direction, i.e., from the beginning of the file and apply some business processing logic on file data according to the application’s requirements.

Sometimes you need to read a file in backward direction, i.e., from the end of the file and you may need to extract last few lines from a file for your application’s need. Then you can use one of the solutions from below code snippets.

I am going to use text file in this example. The sample file can be downloaded later from the source code link given at the bottom of this tutorial.

Related Posts:

• How to read last n lines from a file using Java
• How to read last n line from a file using Python

Prerequisites

Apache HTTP Server 2.4 (Optional), PHP 7.4.3 – 7.4.27

Project Directory

It’s assumed that you have setup Apache and PHP in Windows system.

Now I will create a project root directory called php-file-read-last-n-lines under the Apache server’s htdocs folder or if you are not using HTTP Apache server then you can create the project folder anywhere in the physical drive.

I may not mention the project root directory in subsequent sections and I will assume that I am talking with respect to the project root directory.

Read Last n Lines

Your file may be a small, medium or big depending on your project’s requirements and here I will present with two different solutions you can use according to your need.

Solution – One

When you need to extract last few lines from a small file then you can use below solution.

The sample file license.txt is available in the source code link.

 0) {
		for ($i = $readLines; $i < count($file); $i++) {
			echo $file[$i];
			echo nl2br("\n");
		}
	} else {
		echo 'file does not have required no. of lines to read';
	}

?>

The above solution will consume much memory, so if your file is small then only use the above solution.

Executing the above code will give you the following output assuming n=10:

Solution – Two

This solution will work for your small as well as very big file. I will use here SplFileObject to reduce the memory cost. Use the seek() method to fetch the last line. You should then subtract the current key value by n, where n being the non-zero positive integer.

seek(PHP_INT_MAX);
	$last_line = $file->key();
	$lines = new LimitIterator($file, $last_line - n, $last_line); //n being non-zero positive integer
	print_r(iterator_to_array($lines));
	
	// Iterate each element
	/*$it = iterator_to_array($lines);
	
	foreach($it as $ele){
		echo nl2br($ele . "\n");
	}*/
?>

Executing the above code will give you the following output assuming n=10:

Note that SplFileObject class has a private property that holds the file pointer. Therefore, there is no method to close the file handle, and you get into situations where you are not able to delete the file with unlink() method, because an SplFileObject still has a handle open. Then you have to do some workaround in the following way to delete the file.

$file = new SplFileObject("filename.txt");
$file = null; //explicitly assign null
unlink($file); //now delete the file

That’s all. Hope you got idea how to read last n lines from a file in PHP.

Source Code

Download

How do I make the first line of a file read only in PHP?

How to get lines of a file in PHP?

How do I read the last line of a text file in PHP?

How do you get the first line of a string in PHP?

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