PHP strpos() and stripos() Functions

09 May, 2022
In this article, we will see how to find the position of the first occurrence of a string in another string using strpos() and stripos() Functions in PHP, & will see their implementation through the examples.
Both the strpos() and stripos() Functions in PHP are binary-safe which means the function will handle its input as a raw byte stream and disregard every textual content it may contain. Here, the function will work correctly while passing arbitrary binary data ie., a string having non-ASCII bytes &/or null-bytes.
strpos() Function: This function helps us to find the position of the first occurrence of a string in another string. This returns an integer value of the position of the first occurrence of the string. This function is case-sensitive, which means that it treats upper-case and lower-case characters differently.
Syntax: 
strpos(original_str, search_str, start_pos);
Parameter value: Out of the three parameters specified in the syntax, two are mandatory and one is optional. The three parameters are described below:
original_str: This is a mandatory parameter that refers to the original string in which we need to search the occurrence of the required string.
search_str: This is a mandatory parameter that refers to the string that we need to search.
start_pos: This is an optional parameter that refers to the position of the string from where the search must begin.
Return Type: This function returns an integer value that represents the index of original_str where the string search_str first occurs.
Example: This example illustrates the strpos() function that specifies the position of the occurrence of a string in another string.
PHP
<?php     // PHP code to search for a specific string's position    // first occurrence using strpos() case-sensitive function    function Search($search, $string)    {        $position = strpos($string, $search, 5);        if (is_numeric($position))        {            return "Found at position: " . $position;        }        else        {            return "Not Found";        }    }         // Driver Code    $string = "Welcome to GeeksforGeeks";    $search = "Geeks";    echo Search($search, $string);?>
Output:
Found at position 11
stripos() Function: This function also helps us to find the position of the first occurrence of a string in another string. This returns an integer value of the position of the first occurrence of the string. This function is case-insensitive, which means it treats both upper-case and lower-case characters equally. This function works similarly as strpos(), the difference is that it is case in-sensitive whereas strpos() is case sensitive.
Syntax:  
stripos(original_str, search_str, start_pos);
Parameter value: Out of the three parameters specified in the syntax, two are mandatory and one is optional.
original_str: This is a mandatory parameter that refers to the original string in which we need to search the occurrence of the required string.
search_str: This is a mandatory parameter that refers to the string that we need to find.
start_pos: This is an optional parameter that refers to the position of the string from where the search must begin.
Return Type: This function returns an integer value that represents the index of original_str where the string search_str first occurs.
Example: This example illustrates the stripos() function that specifies the position of the occurrence of a string in another string.
PHP
<?php     // PHP code to search for a specific string    // first occurrence using stripos() case-insensitive function    function Search($search, $string)    {        $position = stripos($string, $search, 5);        if ($position == true)        {            return "Found at position " . $position;        }        else        {            return "Not Found";        }    }         // Driver Code    $string = "Welcome to GeeksforGeeks";    $search = "geeks";    echo Search($search, $string);?>
Output: 
Found at position 11
Let us understand these functions in a tabular form -:
Its syntax is -:
strpos(string,find,start)
Its syntax is -:
stripos(string,find,start)
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