strpos

(PHP 4, PHP 5)

strpos — Find position of first occurrence of a string

说明

int strpos ( string $haystack , mixed $needle [, int $offset=0 ] )

Returns the numeric position of the first occurrence of needle in the haystack string. Unlike the strrpos() before PHP 5, this function can take a full string as the needle parameter and the entire string will be used.

参数

haystack: The string to search in
needle: If needle is not a string, it is converted to an integer and applied as the ordinal value of a character.
offset: The optional offset parameter allows you to specify which character in haystack to start searching. The position returned is still relative to the beginning of haystack .

返回值

Returns the position as an integer. If needle is not found, strpos() will return boolean FALSE.

Warning

本函数可能返回布尔值 FALSE，但也可能返回一个与 FALSE 等值的非布尔值，例如 0 或者 ""。请参阅布尔类型章节以获取更多信息。应使用 === 运算符来测试本函数的返回值。

范例

Example #1 Using ===


<?php
$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);

// Note our use of ===.  Simply == would not work as expected
// because the position of 'a' was the 0th (first) character.
if ($pos === false) {
    echo "The string '$findme' was not found in the string '$mystring'";
} else {
    echo "The string '$findme' was found in the string '$mystring'";
    echo " and exists at position $pos";
}
?>

Example #2 Using !==


<?php
$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);

// The !== operator can also be used.  Using != would not work as expected
// because the position of 'a' is 0. The statement (0 != false) evaluates 
// to false.
if ($pos !== false) {
     echo "The string '$findme' was found in the string '$mystring'";
         echo " and exists at position $pos";
} else {
     echo "The string '$findme' was not found in the string '$mystring'";
}
?>

Example #3 Using an offset


<?php
// We can search for the character, ignoring anything before the offset
$newstring = 'abcdef abcdef';
$pos = strpos($newstring, 'a', 1); // $pos = 7, not 0
?>

注释

Note: 本函数可安全用于二进制对象。

参见

strrpos() - Find position of last occurrence of a char in a string
stripos() - Find position of first occurrence of a case-insensitive string
strripos() - Find position of last occurrence of a case-insensitive string in a string
strrchr() - Find the last occurrence of a character in a string
substr() - Return part of a string
stristr() - Case-insensitive strstr
strstr() - Find first occurrence of a string