PHP crc32() Function
Topic: PHP String ReferencePrev|Next
Description
The crc32() function calculates the 32-bit CRC (cyclic redundancy checksum) for a string.
This function is usually used to validate the integrity of data being transmitted.
The following table summarizes the technical details of this function.
| Return Value: | Returns the crc32 checksum of string as an integer. |
|---|---|
| Version: | PHP 4.0.1+ |
Syntax
The basic syntax of the crc32() function is given with:
The following example shows the crc32() function in action.
Example
Run this code »<?php
// Calculating checksum
$checksum = crc32("The mountain peaks are covered with snow.");
// Printing formatted string
printf("%u\n", $checksum);
?>Warning: Since PHP's integer type is signed many crc32 checksums will result in negative integers on 32bit platforms. On 64bit installations all crc32() results will be positive integers. Therefore, you need to use the "%u" formatter of sprintf() or printf() to get the string representation of the unsigned crc32() checksum in decimal format.
Parameters
The crc32() function accepts the following parameters.
| Parameter | Description |
|---|---|
| string | Required. Specifies the string to work on. |
More Examples
Here're some more examples showing how crc32() function actually works:
In the following example printing checksum with and without the "%u" formatter will be equal.
Example
Run this code »<?php
// Calculating checksum
$checksum = crc32("What happened to John?");
// Printing checksum normally
print $checksum."<br>";
// Printing checksum with "%u" formatter
printf("%u", $checksum);
?>
