[PHP 4, PHP 5, PHP 7, PHP 8]
strpos — Find the position of the first occurrence of a substring in a string
Description
strpos[string $haystack, string $needle, int $offset = 0]:
int|false
Parameters
haystackThe string to search in.
needle Prior to PHP 8.0.0, if needle is not a string, it is converted to an integer and applied as the ordinal value of a character. This behavior is deprecated as of PHP 7.3.0, and relying on it is highly discouraged. Depending on the intended behavior, the needle should
either be explicitly cast to string, or an explicit call to chr[] should be performed.
offsetIf specified, search will start this number of characters counted from the beginning of the string. If the offset is negative, the search will start this number of characters counted from the end of the string.
Return Values
Returns the position of where the needle exists relative to the beginning of the haystack string [independent of offset]. Also note that string positions start at 0, and not 1.
Returns false if the needle was not found.
Warning
This function may return Boolean false, but may also return a non-Boolean value which evaluates to false. Please read the section on
Booleans for more information. Use the === operator for testing the return value of this function.
Changelog
| 8.0.0 | Passing an int as needle is no longer supported.
|
| 7.3.0 | Passing an int as needle has been deprecated.
|
| 7.1.0 | Support for negative offsets has been added.
|
Examples
Example #1 Using ===
Notes
Note: This function is binary-safe.
See Also
- stripos[] - Find the position of the first occurrence of a case-insensitive substring in a string
- str_contains[] - Determine if a string contains a given substring
- str_ends_with[] - Checks if a string ends with a given substring
- str_starts_with[] - Checks if a string starts with a given substring
- strrpos[] - Find the position of the last occurrence of a substring in a string
- strripos[] - Find the position of the last occurrence of a case-insensitive substring in a string
- strstr[] - Find the first occurrence of a string
- strpbrk[] - Search a string for any of a set of characters
- substr[] - Return part of a string
- preg_match[] - Perform a regular expression match
Suggested re-write for pink WARNING box ¶
14 years ago
WARNING
As strpos may return either FALSE [substring absent] or 0 [substring at start of string], strict versus loose equivalency operators must be used very carefully.
To know that a substring is absent, you must use:
=== FALSE
To know that a substring is present [in any position including 0], you can use either of:
!== FALSE [recommended]
> -1 [note: or greater than any negative number]
To know that a substring is at the start of the string, you must use:
=== 0
To know that a substring is in any position other than the start, you can use any of:
> 0 [recommended]
!= 0 [note: but not !== 0 which also equates to FALSE]
!= FALSE [disrecommended as highly confusing]
Also note that you cannot compare a value of "" to the returned value of strpos. With a loose equivalence operator [== or !=] it will return results which don't distinguish between the substring's presence versus position. With a strict equivalence operator [=== or !==] it will always return false.
martijn at martijnfrazer dot nl ¶
10 years ago
This is a function I wrote to find all occurrences of a string, using strpos recursively.
This is how you use it:
fabio at naoimporta dot com ¶
6 years ago
It is interesting to be aware of the behavior when the treatment of strings with characters using different encodings.
lairdshaw at yahoo dot com dot au ¶
7 years ago