What is the replacement function in php string

There are two replacement functions in php strings, namely: 1. substr_replace function, which is used to replace part of a string with another string; 2. str_replace function, which can replace characters with a string other characters in the string.

#The operating environment of this article: Windows7 system, PHP7.1, Dell G3 computer.

PHP String Replacement

Used to replace the specified string from a string.

Related functions are as follows:

• substr_replace(): Replace part of a string with another string
• str_replace(): Use a string to replace characters Other characters in the string

substr_replace()

substr_replace() function is used to replace part of a string with another string and return a mixed type.

Syntax:

mix substr_replace ( mixed string, string replacement, int start [, int length] )

Parameter description is as follows:

Parameter	Description
string	String to be processed
replacement	String to be inserted
start	The starting position of the string, the starting position is 0, if it is negative, it starts from the specified position at the end of the string
length	Optional, the length of the string returned, the default is until the end of the string, if it is negative, it will be returned from the end of the string

Example:

<?php
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1);	//输出 a###
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1, 2);	//输出 a###def
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, -3, 2);	//输出 abc###f
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1, -2);	//输出 a###ef 
?>

Tip

If start is a negative number and length is less than or equal to start, length is 0. [Recommended: PHP Video Tutorial]

str_replace()

str_replace() function uses a string to replace other characters in the string and returns a mixed type.

Syntax:

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

Parameter description is as follows:

Parameter	Description
search	The string to be found (replaced)
replace	The string to be replaced with search
string	The string to be processed
count	Optional, a variable for the replacement count

Example:

<?php
echo str_replace("world","earth","Hello world!");		//输出 Hello earth!
//替换多个，且第二个参数为空字符
echo str_replace("o","","Hello world!");			//输出 Hell wrld! 
//使用数组
$arr = array("e", "o");
$arr2 = array("x", "y");
echo str_replace($arr, $arr2, "Hello World of PHP", $i);	//输出 Hxlly Wyrld yf PHP 
echo $i;							//输出4  
?>

Prompt

1. The difference between this function and substr_replace() is that all those that meet the conditions are replaced
2. This function is case sensitive. For case-insensitive search and replace, use str_ireplace()

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