testing equality for the last digit in a string

[bernie1227]

Hiya guys,
I just thought I might ask a question, just as a change. My question is, I'm testing to see if the last digit of a string is the same as something else (it is meant to ignore the last digit). My problem is however, if there are numbers the same as the last digit, it will ignore them as well, as they are == to the last digit. My problem therefore, is how am I meant to check if is the last digit, rather than equal to the last digit.
thankyasall,
bernie

[djr33]

What's your code? You should be able to get the last digit very easily:
echo $string[strlen($string)-1];

[bernie1227]

At the moment, to get the last digit, I am reversing the string and then getting the first digit, ie the last digit normally. The problem however is digits the same as the last digit being counted as the last digit.

[bernie1227]

so,

$rev = strrev($barcode);
$check = $rev[0];

[jscheuer1]

I read that few a times and I'm still not sure what you're after. Unless it's also always the last character in the string or always a certain distance from the end or beginning of the string, you can use a regular expression to find the last digit character, otherwise a string function would probably be more efficient.. Once it's isolated you can test it against anything you like or just ignore it altogether. That's the part that was the least clear to me.

A regex for last digit would be:

/.*(\d)D*$/

The parenthetical will match the last digit if any in the string. The preg_match function would probably be your best bet to get that match if any.

[bernie1227]

thanks, I'll try it, what I am after is something that specifies the actuall last digit, not the number that is the last digit.

[jscheuer1]

I got the re wrong. It should be:

/.*(\d)[^\d]*$/

Example:

<?php
preg_match('/.*(\d)[^\d]*$/', '1234do9c', $array);
print_r($array);
?>

[djr33]

I'll just repeat what I had above:

What's your code? You should be able to get the last digit very easily:
echo $string[strlen($string)-1];

That will definitively tell you the end of the string.

If you want to COUNT to the end of the string (eg, how long it is), then you can just use:
strlen($string); (subtract 1 if using this for an array key because that starts with 0)

Beyond that, I have no idea what you're talking about. Again, post some code, or post some example numbers that aren't working for you.



John, what you're suggesting would probably work, but there's no reason to use regex here-- the basic string functions will be faster. It's just counting then selecting a digit. I can't imagine regex being faster for that.

[bernie1227]

so my code at the moment is checking a UPC barcode (which is found to be valid via some maths, and if the outcome of the maths is equal to the last digit then, its valid), and in the equations you have to ignore the last digit, and at the moment, my code doing that is then ignoring any numbers that are the same as the final number (the check number). Here is a snippet of my code:

$oddNums = array();
$evenNums = array(); 
$barcode = '123456789999';
$check = $barcode[strlen($barcode)-1];


for($i = 0; $i <= strlen($barcode); $i++){
	$focus = $barcode[$i]; 
	
	if(($i == 0 || ($i % 2) == 0) && $focus != $check){ 
		array_push($oddNums, $focus); 
	}
	if(($i == 1 || (($i % 2) != 0)) && $focus != $check){ 
		array_push($evenNums, $focus);
        }
	
}

[djr33]

Ok. If I'm following:

Last digit:
echo $string[strlen($string)-1];

Everything UNTIL the last digit:
substr($string,0,-1);

Then do what you want with those.



Also, a slightly prettier (but perhaps not faster) way to do the first (find just the last digit) would be:
substr($string,-1);