Question

How can characters ” \n \t \r ” be replaced with ‘-‘ ?

echo preg_replace('/\s/','-','\n\t\n\r\n');//output '\n\t\n\r\n' instead should be'-----'

Edit: I have dynamic content in real app like:

 preg_replace('/\s/','-',$_Request['content']);

can I fix it by adding “” around variable?

preg_replace('/\s/','-',"$_Request['content']");

Edit2:

How can be string converted from format ‘str’ to format “str”?

Thanks

Answer 1

Well, two things. First, the problem is single quotes in your replacement string. Meta-Characters (\n\t\r, etc) are not processed inside of single quotes.

However, don’t use a regex for this. There’s no need for the complexity of the regex. Use

Either use str_replace:

echo str_replace(array("\r", "\n", "\t", "\v"), '-', "\r\n\t\r\v\n\t");

Or strtr:

echo strtr("\r\n\t\r\v\n\t", "\r\n\t\v", '----');

Edit: Ahh, now I see what you’re getting at. You have a string with a literal \r\n\t\r\v\n\t in it, and want to replace them out. Well, you can do that via regex:

$regex = '/(\s|\\\\[rntv]{1})/';
$string = preg_replace($regex, '-', $_GET['content']);

Basically, it matches any space character, and any literal \ followed by either r, n, t or v…