How to detect if a string has a new line break in it?

Question

This doesn\'t work:

$string = \'Hello
    world\';

if(strpos($string, \'\\n\')) {
    echo \'New line break found\';
}
else {
    echo \'not found\';
}
<         


        

Answer 1

The most reliable way to detect new line in the text that may come from different operating systems is:

preg_match('/\R/', $string)

\R comes from PCRE and it is the same as: (?>\r\n|\n|\r|\f|\x0b|\x85|\x{2028}|\x{2029})

The suggested answer to check PHP_EOL

if(strstr($string, PHP_EOL)) {

will not work if you are for example on Windows sytem and checking file created in Unix system.

Answer 2

line break is \r\n on windows and on UNIX machines it is \n. so its search for PHP_EOL instead of "\n" for cross-OS compatibility, or search for both "\r\n" and "\n".

Answer 3

Your existing test doesn't work because you don't use double-quotes around your line break character ('\n'). Change it to:

if(strstr($string, "\n")) {

Or, if you want cross-operating system compatibility:

if(strstr($string, PHP_EOL)) {

Also note that strpos will return 0 and your statement will evaluate to FALSE if the first character is \n, so strstr is a better choice. Alternatively you could change the strpos usage to:

if(strpos($string, "\n") !== FALSE) {
  echo 'New line break found';
}
else {
  echo 'not found';
}