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PHP strings - substr() function

substr() is an usefull function to easily manipulate strings and use them, it returns a custom segment of a whole string.

substr, from position $n to end:
You can extract a small segment from a string from a position $n to the end:

<?php
$part = substr("I'm in Europe now", 7 ); // $part = "Europe now"
?>

Note: position counting start from position 0 !

substr, from position $n1 to $n2 :
You can choose, in substr() parameters, how many characters to extract after the position $n:

<?php
$part = substr("I'm in Europe now", 7 , 6 ); // $part = "Europe"
$part = substr("I'm in Europe now", 7 , 3 ); // $part = "Eur"
?>

Extract $n characters from the end of the string:
You can output the $n last character from a string:

<?php
$part = substr("I'm in Europe now", -3 ); // $part = "now"
?>

Negatif parameters...

You may choose the start position with a negatif number, from the end of the string ( like we see in the previous code):

<?php
$part = substr("I'm in Europe now", -3 ); // $part = "now"
$part = substr("I'm in Europe now", -3 , 2 ); // $part = "no"
?>

If te lenth parameter is negatif, it will count the end of the extracted string from the end...

<?php
$part = substr("I'm in Europe now", 7 , -4 ); // $part = "Europe"
?>

7 is the position whare the extraction should start, and -4 is the ending position counting from the end, so the fourth position from the end is the "e" character...

1 comments

PHP some filesystem functions

files

PHP have many functions to acces and manipulate files, the most important filesystem functions are posted here...

basename() : Returns the filename component from a path.

<?php
$path = "/directory1/index.html";
echo basename($path); // display: index.html
echo basename($path ,".html" ); // display: index
?>

file_exists() : Checks if a file or directory exists ot not.

<?php
echo file_exists("test.txt"); // returns True if exists, otherwise returns False
?>

rename() : Renames a file or directory.

<?php
rename("dir1","dir2"); // You can rename a file or a folder
?>

copy() : Copies a file.

<?php
copy("sourcefile.txt","destinationfile.txt");
?>

unlink() : Deletes a file.

<?php
unlink("file.txt"); // returns True if deleted successfully, False if not deleted.
?>

filesize() : Returns the size of the file.

<?php
echo filesize("file.txt"); // returns the size of file.txt in bytes, or False in failure.
?>

filetype() : Returns the file type.

<?php
echo filetype("file.txt"); // returns type: file.
//Possible types are: file, dir, link, block, char, fifo, unknown.
?>

is_readable() : Checks whether a file is readable, returns true if yes.
is_writable() : Checks whether a file is writeable, returns true if yes.

fileperms() : Returns the permissions of a file.
filemtime() : Returns the last modification time of a file, Display a number in second, to convert it to humain redable date format, use:

<?php
echo date("F d Y H:i:s", filemtime("test.txt")); // returns date format: September 03 2008 18:27:35
?>

If you have any question, or need more details or functions, post a comment here.

1 comments

Get Filename without extension

files

Hello,

It's sometimes usefull to pick the name of the file without its extension, and this is very easy with php !

PHP Code:

<?php
$arr = explode(".", $allname);
$filename = $arr[0];
?>

But this script will not work the file name is dotted, in that case use this:

PHP Code:

<?php
$filename = preg_replace( '/\.[a-z0-9]+$/i' , '' , 'dotted.file.Name' );
?>

Or:

<?php
$FileNameTokens = explode('.', $allname);
$fileName = implode(".", array_slice($FileNameTokens, 0, count($FileNameTokens) - 1));
?>

If this is a few hard to understand, this script is easier:

PHP Code:

<?php
function getFilenameWithoutExt($filename){
$pos = strripos($filename, '.');
if($pos === false){
return $filename;
}else{
return substr($filename, 0, $pos);
}
}
?>