different output from same function with same parameters

Question

I am confused with following string function

echo strlen("l\n2"); //give 3 in output

where as

echo strlen('l\n2'); //give 4 in output

can anybody explain why ?

Answer 1

Because when you use single quotes (' '), PHP does not expand the \n as a single new line character whereas in double quotes (" "), \n translates to the new line character (ie. a single character) thus giving 3 characters

Taken from PHP's String Documentation: http://php.net/manual/en/language.types.string.php

Note: Unlike the double-quoted and heredoc syntaxes, variables and escape sequences for special characters will not be expanded when they occur in single quoted strings.

Answer 2

\n is not parsed as a newline character when the string is wrapped in single quotes. Instead, it is treated as a literal \ followed by n.