How to replace a string with a given substring in php

Replacement method: 1. Use the "substr_replace()" method to replace part of the string with another string; 2. Use the "str_replace()" method to achieve replacement; 3. Use "str_ireplace()" The method can be replaced.

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

Method 1: Use substr_replace() function

substr_replace() function replaces part of a string with another string.

The syntax of the substr_replace() function is as follows:

mixed substr_replace ( mixed $string , mixed $replacement , mixed $start [, mixed $length ] )

This function accepts three required parameters $string, $replacement (replacement value) and $start (the position where the replacement starts), and an omissible parameter $length (the number of characters to be replaced). The

substr_replace() function makes a copy of the string $string a substring qualified by the $start and $length parameters. Strings are replaced using $replacement.

To put it simply, use the $replacement value to start from the $start position (note, the string position starts from 0), Replace $length characters.

Example:

<?php
$str = &#39;hello,world,hello,world&#39;;
$replace = &#39;***&#39;;
echo substr_replace($str, $replace, 0,5)."<br>";
echo substr_replace($str, $replace, 6,5)."<br>";
?>

##Method 2: Use str_replace() function

str_replace() function replaces some characters in a string with other characters (case sensitive).

Syntax:

str_replace($search,$replace,$string,$count)

This function can replace some characters in the string in a case-sensitive manner; the function accepts three required parameters $search (substring to be searched), $replace (the value to be replaced), $string (a string), and an optional parameter $count (a variable).

Example:

<?php
$str = &#39;hello,world,Hello,World&#39;;
$replace = &#39;***&#39;;
$search1 = &#39;hello&#39;;
$search2 = &#39;world&#39;;
echo str_replace($search1, $replace, $str)."<br>";
echo str_replace($search2, $replace, $str)."<br>";
?>

Method 3: Use str_ireplace() function

The str_replace() function replaces some characters in a string (case sensitive).

Syntax:

str_ireplace($search,$replace,$string,$count)

This function can ignore some characters in the replacement string, ignoring case. The parameters accepted by this function are the same as the str_replace() function. The first three parameters are Required (cannot be omitted), the latter parameter $count is omissible (but if set, the number of substitutions can be obtained).

The parameter $count can accept a variable to count the number of substitutions; if this parameter is set, you can know how many substitutions have been performed in total.

Example:

<?php
header("Content-Type: text/html;charset=utf-8");    //设置字符编码
$str = &#39;hello,world,Hello,World&#39;;
$replace = &#39;***&#39;;
$search1 = &#39;hello&#39;;
$search2 = &#39;world&#39;;
echo str_ireplace($search1, $replace, $str, $i)."<br>";
echo  "一共执行了  $i"." 次替换<br><br>";

echo str_ireplace($search2, $replace, $str, $i)."<br>";
echo  "一共执行了  $i"." 次替换<br><br>";
?>

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