Working with PHP Octals and String conversions

问题

I'm working with a database that has a bunch of serial numbers that are prefixed with leading 0's.

So a serial number can look like 00032432 or 56332432.

Problem is with PHP I don't understand how the conversion system with octals works.

A specific example is that I'm trying to convert and compare all of these integer based numbers with strings.

Is it possible to convert an octal, such as 00234 to a string like "00234" so that I can compare it?

edit - adding a specific example. I would like to be able to run str functions on the serial like below.

  $serial = 00032432; // coming from DB

  if(substr($serial, 0, 1) == '0') {

        // do something

   }

回答1:

When you convert with (string) $number, you always get a string in decimal base, it doesn't matter if you write the number in octal mode or in decimal mode, an int is an int and it has not itself a base. It's his string representation that have to be interpreted with a base.

You can get the octal string representation of a number in this way:

$str = base_convert((string) 00032432, 10, 8);

or giving the number in decimal rep:

$str = base_convert((string) 13594, 10, 8);

or, more concisely but less clearly:

 $str = base_convert(00032432, 10, 8);
 $str = base_convert(13594, 10, 8);

In the last the string conversion is made implicitly. The examples give all as result $str = "32432".

base_convert converts a string representation of a number from a base to another

If you want also the zeros in your string, you can add them with simple math.

Hope this can help you.

回答2:

To convert an octal to a string, cast it:

$str = (string) 00032432;

You can convert between octal and decimal with the functions octdec and decoct

<?php
echo octdec('77') . "\n";
echo octdec(decoct(45));
?>

http://uk.php.net/manual/en/function.octdec.php

回答3:

$str = sprintf('%o', $octal_value);

回答4:

$serial = 00032432; //here you have an octal number
$serial= strval($serial); //now you have a string
if ($serial[0]=="0") {
 //do something
}

回答5:

Everything from the database is automatically a string. Integers are strings, dates are strings, dogs are strings.

If you are doing something weird, convert anything to a string by: $a = (string) 12;

来源：https://stackoverflow.com/questions/2495611/working-with-php-octals-and-string-conversions

标签

php

string

octal