Summary of php substr function definition and usage (2022)

php substr is a functional function developed based on the PHP language that can return a part of a string. Sometimes when we use php substr, some garbled characters will appear. How to solve it?

php substr basic syntax

string substr ( string $string , int $start [, int $length ] )

Returns a string of length starting from the start position in the string. The substr function intercepts characters by bytes. Chinese characters are 2 bytes in GB2312 encoding and 3 bytes in UTF-8 encoding. Therefore, if Chinese characters are truncated when intercepting a string of specified length, the returned result will be garbled.

php substr Parameters

Required. Specifies a part of the string to be returned.

php substr 返回值

返回提取的子字符串， 或者在失败时返回 FALSE。

php substr 示例

1、基本使用

<?php
echo substr(&#39;abcdef&#39;, 1);     // bcdef
echo substr(&#39;abcdef&#39;, 1, 3);  // bcd
echo substr(&#39;abcdef&#39;, 0, 4);  // abcd
echo substr(&#39;abcdef&#39;, 0, 8);  // abcdef
echo substr(&#39;abcdef&#39;, -1, 1); // f

// 访问字符串中的单个字符
// 也可以使用中括号
$string = &#39;abcdef&#39;;
echo $string[0];                 // a
echo $string[3];                 // d
echo $string[strlen($string)-1]; // f
?>

2、高性能使用

<?php
class apple {
    public function __toString() {
        return "green";
    }
}

echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL;
echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL;
echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL;
echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL;
echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL;
echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL;
echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL;
?>

php substr 常见问题

1. 如何解决php substr乱码问题

简介：substr函数在截取字符时是按字节来截取的，中文字符在GB2312编码时为2个字节，utf-8编码时为3个字节，所以截取指定长度的字符串时如果截断了汉字，那么返回的结果显示出来便会出现乱码。

2. 关于PHP substr()函数的几个程序

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3. php substr()函数处理中文详解

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7. php substr中文乱码解决办法

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8. PHP substr截取字符串时，中文出现乱码的问题解决

简介：:本篇文章主要介绍了PHP substr截取字符串时，中文出现乱码的问题解决，对于PHP教程有兴趣的同学可以参考一下。

9. php substr截断中文半个汉字乱码问题的解决方法

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Parameters	Description
##string
start	Required. Specifies where in the string to begin. Positive numbers - start at the specified position in the string Negative numbers - start at the specified position from the end of the string 0 - Starts at the first character in the string
length	Optional. Specifies the length of the returned string. The default is until the end of the string. Positive number - the length returned from the position of the start parameter Negative number - the length returned from the end of the string length