PHP substr_compare() Function

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Compare two strings:

echo substr_compare("Hello world","Hello world",0);
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Definition and Usage

The substr_compare() function compares two strings from a specified start position.

Tip: This function is binary-safe and optionally case-sensitive.



Parameter Description
string1 Required. Specifies the first string to compare
string2 Required. Specifies the second string to compare
startpos Required. Specifies where to start comparing in string1. If negative, it starts counting from the end of the string
length Optional. Specifies how much of string1 to compare
case Optional. A boolean value that specifies whether or not to perform a case-sensitive compare:
  • FALSE - Default. Case-sensitive
  • TRUE - Case-insensitive

Technical Details

Return Value: This function returns:
  • 0 - if the two strings are equal
  • <0 - if string1 (from startpos) is less than string2
  • >0 - if string1 (from startpos) is greater than string2
If length is equal or greater than length of string1, this function returns FALSE.
PHP Version: 5+
Changelog: As of PHP 5.1, it is now possible to use a negative startpos

More Examples

Example 1

Compare two strings, when start position in string1 for the comparison is 6th:

echo substr_compare("Hello world","world",6);
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Example 2

Using all parameters:

echo substr_compare("world","or",1,2);
echo substr_compare("world","ld",-2,2);
echo substr_compare("world","orl",1,2);
echo substr_compare("world","OR",1,2,TRUE);
echo substr_compare("world","or",1,3);
echo substr_compare("world","rl",1,2);
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Example 3

Different return values:

echo substr_compare("Hello world!","Hello world!",0); // the two strings are equal
echo substr_compare("Hello world!","Hello",0); // string1 is greater than string2
echo substr_compare("Hello world!","Hello world! Hello!",0); // str1 is less than str2
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