PHP substr_compare() Function

The substr_compare() function is a built-in function in PHP and it helps to compare two strings from a specified start position upto a specified length. 

Syntax:

int substr_compare($str1, $str2, $startpos, $len, $caseInsensitive)

Parameters: This function accepts a total of five parameters out of which first three are mandatory to be supplied and the rest two are optional. All of these parameters are described below:

1. $str1(mandatory): This parameter represents the first string to compare.
2. $str2(mandatory): This parameter represents the second string to compare.
3. $startpos(mandatory): This parameter specifies where to start comparing in $str1. If startpos is negative then it starts comparing from the end of the string.
4. $len(optional): This parameter specifies how much of $str1 to compare.
5. $caseInsensitive(optional): This parameter represents a boolean value that specifies whether or not to perform a case-sensitive comparison. If it is set to FALSE then the comparison will be Case-sensitive, If it is set to TRUE then the comparison will be Case-insensitive

Return Value: This function returns an integer value based on the below cases:

• Returns a value less than 0 if $str1 starting from position $startpos is less than str2.
• Returns a value greater than 0 if $str1 starting from position $startpos greater than string2.
• Returns 0 if $str1 and $str2 are equal.
• If $startpos is equal to or greater than the length of $str1, or the length $len is set and is less than 1 then substr_compare() function prints a warning and returns FALSE.

Below program illustrate the substr_compare() Function in PHP: 

php

<?php

// PHP program to illustrate the
// substr_compare() function

echo substr_compare("geeks", "gfg", 2)."\n";
echo substr_compare("geeksforgeeks", "gfg", 2)."\n";
echo substr_compare("Geeks", "gfg", 0, 1, true)."\n";
echo substr_compare("Geeks", "gfg", 0, 3, true)."\n";
echo substr_compare("GeeksforGeeks", "geeksforgeeks",
                                    0, false)."\n";

?>

Output:

-2
-2
0
-1
0

Reference: http://php.net/manual/en/function.substr-compare.php