substr_count()
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。