PHP crc32() Function

Example

Print the result of crc32():

<?php
$str = crc32("Hello World!");
printf("%u\n",$str);
?>

Definition and Usage

The crc32() function calculates a 32-bit CRC (cyclic redundancy checksum) for a string.

This function can be used to validate data integrity.

Tip: To ensure that you get the correct string representation from the crc32() function, you'll need to use the %u formatter of the printf() or sprintf() function. If the %u formatter is not used, the result may display in incorrect and negative numbers.

Syntax

crc32( string)

Parameter Values

Parameter	Description
string	Required. The string to be calculated

Technical Details

Return Value:	Returns the crc32 checksum of string as an integer
PHP Version:	4.0.1+

More Examples

Example:

In this example we will print the result of crc32() with and without the "%u" formatter (note that the result is equal):

<?php
$str = crc32("Hello world!");
echo 'Without %u: '.$str."<br>";
echo 'With %u: ';
printf("%u",$str);
?>

The output of the code above will be:

Without %u: 461707669
With %u: 461707669

Example:

In this example we will print the result of crc32() with and without the "%u" formatter (note that the result is not equal):

<?php
$str = crc32("Hello world.");
echo 'Without %u: '.$str."<br>";
echo 'With %u: ';
printf("%u",$str);
?>

The output of the code above will be:

Without %u: -1959132156
With %u: 2335835140

❮ PHP String Reference