String Comparison Issues

PHP
1

The scenario is this:

  1. I keep a default value for a string in a config file.
  2. This value is used to populate a textarea in a form.
  3. User can change the text in the textarea if he/she chooses and submits
  4. I compare the $_POST value with the config value to see if there are any changes.

The problem I’m having is that strcmp, ==, and === all evaluate to false even if the text hasn’t changed.

I’ve checked and it doesn’t appear that the form is inserting any extra chars…

Any ideas?

2

Do you trim() the input value?

3

That function returns 0 when the strings match.


if(strcmp('yes','yes')) {
echo 'not equal';
} else {
echo 'equal';
}

Therefore, you may be getting the return values mixed up. In this case the function is going to return false (0) when there is a match and true (!0) when not a match. Although you may expect it to work the opposite way but that is not the case due the return value complexity for non-matches.

http://php.net/manual/en/function.strcmp.php