I must not completely understand PHP's trim() function

Question

I was noticing some odd results in the output of my code that I traced back to trim(). I tested and verified my result at phptester.net (please go ahead and verify). How does the following small script give the result shown?

$x = "d1d1d1";
define("REP", "xqzxqjb1");

echo trim($x, REP); //the output is the string 'd1d1d'

//Same result if $x = 'xqzxqjb1d1d1d1xqzxqjb1' OR $x = 'd1d1d1xqzxqjb1' OR $x = 'xqzxqjb1d1d1d1';

Why isn't the output 'd1d1d1' for any of these?

The second argument is a character mask: http://php.net/manual/en/function.trim.php ; Also note, that it trims only from the **start and the end**! — Rizier123, Jul 28 '15 at 21:29
REP is just the constant name...could be anything but I mean it to be "REPlacement" in my code — The One and Only ChemistryBlob, Jul 28 '15 at 21:31
OK...thanks. I went to the link for the other question. That is unbelievable that PHP cannot do this w/o preg_replace()...if I could downvote PHP as a whole at this point I would ;p — The One and Only ChemistryBlob, Jul 28 '15 at 21:38

score 4 · Answer 1 · answered Jul 28 '15 at 21:31

4

Why shouldn't it be?

trim() - Strip whitespace (or other characters) from the beginning and end of a string

trim('d1d1d1', 'xqzxqjb1');
                  ^---remove these chars from the string

x,q,z,x,q,j,b - not in string, ignore
1 - present at the END of the string, strip it:

php > echo trim('d1d1d1', "xqzxqjb1");
d1d1d
     ^---see, no 1

answered Jul 28 '15 at 21:31

Marc B

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OK, I thought the function trimmed the entire string from the ends, not all the characters as individual characters. How do I remove the entire string from the ends without str_replace()? – The One and Only ChemistryBlob Jul 28 '15 at 21:33
1

given that question, marking this whole thing as a dupe... – Marc B Jul 28 '15 at 21:35

score 0 · Answer 2 · answered Jul 28 '15 at 21:34

0

Because trim will remove any number of any of those characters from the ends of a string, not (as you seem to think) the entire string.

In all cases, you end up with d1d1d because that's the central part of the string after stripping away the characters in REP.

answered Jul 28 '15 at 21:34

paxdiablo

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OK...thanks. The function I need is to trim the entire substring only from the ends, which is what I thought trim() did. Is there any built-in PHP function, not str_replace(), which removes the entire string from either end of another string? – The One and Only ChemistryBlob Jul 28 '15 at 21:36
@TheOneandOnlyChemistryBlob : You are probably going to want to look in to regular expressions for this. – Jerbot Jul 28 '15 at 21:37

I must not completely understand PHP's trim() function

2 Answers2