single quotes

[etsted]

$previous = '';

$paginationCtrls .= '<a href=" ' . $_SERVER['PHP_SELF']. '?pn=$previous">Previous</a>';

$paginationCtrls .= '<a href="$_SERVER['PHP_SELF']?pn=$previous">Previous</a>';

 

only the second code Works, becuase i have used single quote concatination, why doesnt the third line work?

[justsomeguy]

Because the quotes around PHP_SELF are breaking the rest of the string.

[etsted]

But wont the double quotes keep it all together?

[thescientist]

not in the third example, because you have single quote, double quote, then single quote. It considers the second single quote the end of the first one.

[justsomeguy]

The double quote is part of the data inside the string. It has no special meaning, it's just a character like any other character inside the string.

[etsted]

but u are supposed to use them With links

[Ingolme]

Not necessarily, but you need to read the code from left to right. When a quotation mark appears, the string is open, when the same type of quotation mark appears again the string is closed. Syntax highlighters do this for you. You should be able to see clearly here:

$paginationCtrls .= '<a href=" ' . $_SERVER['PHP_SELF']. '?pn=$previous">Previous</a>';$paginationCtrls .= '<a href="$_SERVER['PHP_SELF']?pn=$previous">Previous</a>';

You can use double-quotes and complex string syntax. That requires escaping any double-quotes that are in the string with

<?php$paginationCtrls .= "<a href="{$_SERVER['PHP_SELF']}?pn=$previous">Previous</a>";?>

[justsomeguy]

but u are supposed to use them With links

PHP doesn't care what is in the string. It doesn't matter to PHP if you have a string of HTML code or whatever else. PHP has no knowledge about what you are outputting, it will not validate HTML code for you for example. As far as PHP knows, you start a string with a single quote, the next single quote ends the string, and then it sees a bunch of stuff it doesn't understand. It doesn't matter if it is HTML or a link or anything else.