trim() function : How to avoid empty string return if the argument is unset/null variable?

Question

I have a problem when using the trim() function in php.

//Suppose the input variable is null.
$input = NULL;
echo (trim($input));

As shown above, the output of the codes is empty string if the input argument if NULL. Is there any way to avoid this? It seems the trim will return empty string by default if the input is unset or NULL value.

This give me a hard time to use trim as following.

array_map('trim', $array);

I am wondering if there's any way I can accomplish the same result instead of looping through the array. I also noticed that the trim function has second parameter, by passing the second parameter, you can avoid some charlist. but it seems not work for me.

Any ideas? Thanks.

Trim expects a string input, so PHP is trying to be helpful and is typecasting the null into an empty string. — Marc B, Feb 12 '11 at 01:47
@Jonah I try to use array_map('trim', $array).. but this will filter out the NULL variable. — easycoder, Feb 12 '11 at 20:42
@easycoder: you're saying that your program needs to make the distinction between null and empty strings? — Jonah, Feb 13 '11 at 01:16

Jonah · Accepted Answer · 2011-02-13T03:56:32.633

11

Create a proxy function to make sure it's a string before running trim() on it.

function trimIfString($value) {
    return is_string($value) ? trim($value) : $value;
}

And then of course pass it to array_map() instead.

array_map('trimIfString', $array);

edited Feb 13 '11 at 03:56

answered Feb 12 '11 at 01:43

Jonah

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thanks for your reminding... the proxy function seems good to me.. i will try that out.. :) – easycoder Feb 13 '11 at 04:06

score 4 · Answer 2 · edited Jun 10 '21 at 21:36

4

Why not just:

$input = !empty($input) ? trim($input) : $input;

edited Jun 10 '21 at 21:36

Gabriel Fernandez

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answered Feb 12 '11 at 01:41

Mikel

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Yes, just realized that. Thanks. – Mikel Feb 12 '11 at 01:46
I am used to using `isset()`, because you normally want to treat null and an empty string as equivalent, as you said in your answer. ;-) – Mikel Feb 12 '11 at 01:55
Looks like I had things backwards after changing `isset` to `is_null`. Should be fixed now. Let me know if that works. – Mikel May 23 '16 at 00:13

trim() function : How to avoid empty string return if the argument is unset/null variable?

2 Answers2