PHP substr_count() 函数
PHP 教程
· 2019-01-30 13:57:20
实例
计算 "world" 在字符串中出现的次数：
<?php
echo substr_count("Hello world. The world is nice","world");
?>
echo substr_count("Hello world. The world is nice","world");
?>
substr_count() 函数计算子串在字符串中出现的次数。
注释：子串是区分大小写的。
注释：该函数不计数重叠的子串（参见实例 2） 。
注释：如果 start 参数加上 length 参数大于字符串长度，该函数则生成一个警告（参见实例 3）。
语法
substr_count(string,substring,start,length)
| 参数 | 描述 |
|---|---|
| string | 必需。规定要检查的字符串。 |
| substring | 必需。规定要检索的字符串。 |
| start | 可选。规定在字符串中何处开始搜索。 |
| length | 可选。规定搜索的长度。 |
技术细节
| 返回值： | 返回子串在字符串中出现的次数。 |
|---|---|
| PHP 版本： | 4+ |
| 更新日志： | 在 PHP 5.1 中，新增了 start 和 length 参数。 |
更多实例
实例 1
使用所有的参数：
<?php
$str = "This is nice";
echo strlen($str)."<br>"; // Using strlen() to return the string length
echo substr_count($str,"is")."<br>"; // The number of times "is" occurs in the string
echo substr_count($str,"is",2)."<br>"; // The string is now reduced to "is is PHP"
echo substr_count($str,"is",3)."<br>"; // The string is now reduced to "s is PHP"
echo substr_count($str,"is",3,3)."<br>"; // The string is now reduced to "s i"
?>
$str = "This is nice";
echo strlen($str)."<br>"; // Using strlen() to return the string length
echo substr_count($str,"is")."<br>"; // The number of times "is" occurs in the string
echo substr_count($str,"is",2)."<br>"; // The string is now reduced to "is is PHP"
echo substr_count($str,"is",3)."<br>"; // The string is now reduced to "s is PHP"
echo substr_count($str,"is",3,3)."<br>"; // The string is now reduced to "s i"
?>
实例 2
重叠的子串：
<?php
$str = "abcabcab";
echo substr_count($str,"abcab"); // This function does not count overlapped substrings
?>
$str = "abcabcab";
echo substr_count($str,"abcab"); // This function does not count overlapped substrings
?>
实例 3
如果 start 和 length 参数超过字符串长度，该函数则输出一个警告：
<?php
echo $str = "This is nice";
substr_count($str,"is",3,9);
?>
echo $str = "This is nice";
substr_count($str,"is",3,9);
?>
由于长度值超过字符串的长度（3 + 9大于12）。所以这将输出一个警告。
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