quoting constants in php: “this is a MY_CONSTANT”

问题

I want to use a constant in PHP, but I also want to put it inside double quotes like a variable. Is this at all possible?

define("TESTER", "World!");
echo "Hello, TESTER";

obviously outputs "Hello, TESTER", but what I really want is something like:

$tester = "World!";
echo "Hello, $tester";

outputs "Hello, World!".

回答1:

Sorry, that's not the way constants in PHP work. You can put variables in double quotes and heredocs but not constants.

回答2:

I recomend you to use concatenation because:

1. When you use a variable into a double quotes string your visibility is not good;
2. When you use a double quotes string the php can to process slowly;
3. You don't use a constant into a string, because don't have any delimiter to the php knows what is the constant.

回答3:

Concatenation is the way to go.

Unless you want the hokey, nasty, inefficient, evil monkey way of:

echo preg_replace("/TESTER/",TESTER,$original_content);

回答4:

no way, unless you write your own string parsing function

回答5:

I've found that when dot-concatenation of a constant is a problem, using sprintf to get my string is usually the way I want to go in the end.

回答6:

Alternatively, do

"this is " . MY_CONSTANT

or

"this is " . constant("MY_CONSTANT");

来源：https://stackoverflow.com/questions/1563654/quoting-constants-in-php-this-is-a-my-constant