PHP crc32() Function
Example
Print the result of crc32():
<?php
$str = crc32("Hello World!");
printf("%u\n",$str);
?>
Run example »
$str = crc32("Hello World!");
printf("%u\n",$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 | 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+ |
Example 1
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);
?>
$str = crc32("Hello world!");
echo 'Without %u: '.$str."<br>";
echo 'With %u: ';
printf("%u",$str);
?>
The output of the code above will be:
Without %u: 461707669
With %u: 461707669
With %u: 461707669
Example 2
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);
?>
$str = crc32("Hello world.");
echo 'Without %u: '.$str."<br>";
echo 'With %u: ';
printf("%u",$str);
?>
The output of the code above will be:
Without %u: -1959132156
With %u: 2335835140
With %u: 2335835140
PHP String Reference
