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
– Marc B, Commented Feb 12, 2011 at 1:47
@Jonah I try to use array_map('trim', $array).. but this will filter out the NULL variable. — easycoder
– easycoder, Commented Feb 12, 2011 at 20:42
@easycoder: you're saying that your program needs to make the distinction between null and empty strings? — Jonah
– Jonah, Commented Feb 13, 2011 at 1:16

Jonah · Accepted Answer · 2011-02-13 03:56:32Z

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);

thanks for your reminding... the proxy function seems good to me.. i will try that out.. :)

Gabriel Fernandez · Accepted Answer · 2021-06-10 21:36:29Z

4

Why not just:

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

edited Jun 10, 2021 at 21:36

Gabriel Fernandez

3834 silver badges8 bronze badges

answered Feb 12, 2011 at 1:41

Mikel

25.9k8 gold badges70 silver badges66 bronze badges

3 Comments

Mikel Over a year ago

Yes, just realized that. Thanks.

Mikel Over a year ago

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 Over a year ago

Looks like I had things backwards after changing isset to is_null. Should be fixed now. Let me know if that works.

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