Take you to quickly master PHP string replacement (detailed examples)

In the previous article "Methods and restoration of escaped strings in PHP (detailed examples)" we introduced in detail how to operate escaped strings in PHP and how to restore them. In this article, we will take a look at the relevant knowledge of string replacement in PHP. I hope it will be helpful to everyone!

In the previous article we talked about how to add characters through the addslashes() function and the stripslashes() function Escape and restore strings. Escape strings are a very common operation in the development process. The same replacement operation of strings is also very common.

In PHP, if you want to complete the replacement of a string or the replacement of specific characters in a string, you can use the substr_replace function and str_replace function provided by PHP. How should these two functions be used and what are the differences between them? Let us take a look at them next.

<strong><span style="font-size: 20px;">substr_replace()</span></strong>Function - Replace part of a string

If you want to replace part of a string in PHP, you can use the substr_replace() function provided by PHP. The basic syntax format of the substr_replace() function is as follows:

substr_replace(string,replacement,start,length)

It should be noted that the parameter string represents the string that needs to be replaced, and the parameter replacement represents the string to be inserted, that is, the character to be replaced. String, the parameter start represents the position from which the string should be replaced, and the parameter length represents the length of the replacement.

If the parameter start is a positive number, the replacement position will be calculated from the position of the parameter start. If the parameter start is a negative number, the replacement position will be calculated from the position of the parameter start. The replacement position is calculated from the end to the start position. If it is

0

, start from the first position. If the parameter length is a positive number, it indicates the length of the number of characters to be replaced. If it is a negative number, it indicates the number of characters from the end of the substring to be replaced to the end of string. If it is 0, it indicates direct insertion. Not a replacement. Also, if start is a negative number and length is less than or equal to start, then length is

0

.

The result returned by this function is the replaced string.

Let’s take a look at the use of the substr_replace() function through an example. The example is as follows:

<?php
$str = &#39;abcdef&#39;;
$replace = &#39;###&#39;;
echo substr_replace($str, $replace, 0,5);
echo &#39;<br/>&#39;;
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1);    //输出 a###
echo &#39;<br/>&#39;;
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1, 2); //输出 a###def
echo &#39;<br/>&#39;;
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, -3, 2);    //输出 abc###f
echo &#39;<br/>&#39;;
echo substr_replace(&#39;abcdef&#39;, &#39;###&#39;, 1, -2);    //输出 a###ef
?>

Output result:

In the above example, part of the string can be replaced through the substr_replace() function. Next, let's take a look at the use of the str_replace function. <strong><span style="font-size: 20px;"></span></strong>str_replace Function

We have been able to pass the The substr_replace() function replaces part of a string with another string, while the

str_replace

function can use a string to replace other characters in a string. The basics of the str_replace function The syntax format is as follows: <pre class='brush:php;toolbar:false;'>str_replace(find,replace,string,count)</pre> What we need to pay attention to is that the parameter find represents the value to be found, the parameter replace represents the value to be replaced, and the parameter string indicates the specified string to be searched, and the parameter

count

indicates the variable that counts the number of replacements.

The return value of this function is a string or array with a replacement value. Next, let’s look at the use of the str_replace function through an example. The example is as follows:

<?php
echo str_replace("world","earth","Hello world!") . &#39;<br/>&#39;;       //输出 Hello earth!
//替换多个，且第二个参数为空字符
echo str_replace("o","","Hello world!") . &#39;<br/>&#39;;            //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) . &#39;<br/>&#39;;    //输出 Hxlly Wyrld yf PHP
echo $i;                            //输出4 
?>

Output result:

In the above example, a string is used to replace other characters in the string through the str_replace function. Let's look at another example:

<?php
$arr = array("blue","red","green","yellow");
print_r(str_replace("red","pink",$arr,$i));
echo &#39;<br/>&#39; . "替换数：$i" . &#39;<br/>&#39;;
$find = array("Hello","world");
$replace = array("B");
$arr1 = array("Hello","world","!");
print_r(str_replace($find,$replace,$arr1));
?>

Output result:

This means that the elements that need to be replaced are less than the elements found through the str_replace function. Both the str_replace function and the substr_replace() function above can achieve the purpose of replacing strings. If you are performing case-insensitive search and replacement, it is recommended to use

str_ireplace

() function. If you are interested, you can click on "

PHP Video Tutorial###" to learn more about PHP knowledge. ###

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