How to delete special strings in php

How to delete special strings in php: 1. Use trim to remove the blank characters at the beginning and end of the string; 2. Use ltrim to delete the blank characters at the beginning of the string; 3. Use rtrim to delete the space characters at the end of the string. ;4. Replace and delete through str_replace function.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

How to delete special strings in php?

Removing special characters from PHP strings

The functions to remove special characters from strings include trim, ltrim, rtrim, str_replace

1, trim--remove characters Blank characters (or other characters) at the beginning and end of the string

Syntax:

String trim(string $str[,string $charlist])

String trim: Returns the string type

string $str: The string to be processed

string $charlist: Optional, the characters to be filtered (once specified, only the specified characters can be removed, and the default ones will not be removed)

For example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
 
$str = &#39; #123456# &#39;;
 
echo trim($str);//#123456#
echo trim($str,#);// 123456
?>

But when using the default special symbols other than spaces, you need to use double quotes and cannot use single quotes

For example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
 
$str=&#39; \t123456 &#39;;
echo trim($str);//\t123456
 
$st = " \t123456 ";
echo trim($st);//123456
?>

Any characters except the beginning and the end cannot be removed

For example:

<?php
header(content-type:text/html;charset=utf-8);
 
$str = " 123 456 ";
echo trim($str);//123 456
?>

2. ltrim--delete the blank characters (or other characters) at the beginning of the string

The syntax is the same as trim

For example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
 
$str = " \n123 456 ";
echo ltrim($str);//123 456 
$str = "# 123 456#";
echo ltrim($str,&#39;#&#39;);// 123 456#
echo ltrim($str,&#39; #&#39;);//123 456#
?>

3. rtrim--delete the space character (or other characters) at the end of the string

The syntax is the same as trim

For example Bar:

<?php
header(content-type:text/html;charset=utf-8);
 
$str = " #123 456\n ";
echo rtrim($str);// #123 456
$str = " #123 456 #";
echo rtrim($str,&#39; #&#39;);// #123 456
?>

4, str_replace--substring replacement

mixed str_replace(mixed $search,mixed $replace,mixed $subject[,int &$count])

mixed: mixed

mixed $search: find the target value

mixed $ replace: Replacement value of the target value

mixed $subject: Array or string to perform replacement

int &$count: Optional, the number of times the replacement occurs

For example Example:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
$str = "#123456#";
echo str_replace(&#39;#&#39;,&#39;&#39;,$str);//123456
?>

When you want to replace multiple characters, you need to use an array to replace them

<?php
header(&#39;count-type:text/html;charset=utf-8&#39;);
$str = " #123 #456 ";
echo str_replace(array(&#39; &#39;,&#39;#&#39;),array(&#39;&#39;,&#39;&#39;),$str);//123456
?>

trim, ltrim, rtrim are special characters that can be removed by default

“”，普通空格字符
“\t”,制表符
“\n”,换行
“\r”,回车
“\o”,字节符
“\xoB”,垂直制表符

Recommended learning: "PHP Video Tutorial"

The above is the detailed content of How to delete special strings in php. For more information, please follow other related articles on the PHP Chinese website!