PHP Function to Join Strings?

Question

join_strings(string $glue, string $var, string $var2 [, string $...]);

I am looking for something that would behave similar to the function I conceptualized above. A functional example would be:

$title = "Mr.";
$fname = "Jonathan";
$lname = "Sampson";

print join_strings(" ", $title, $fname, $lname); // Mr. Jonathan Sampson

After giving the documentation a quick look-over, I didn't see anything that does this. The closest I can think of is implode(), which operates on arrays - so I would have to first add the strings into an array, and then implode.

Is there already a method that exists to accomplish this, or would I need to author one from scratch?

Note: I'm familiar with concatenation (.), and building-concatenation (.=). I'm not wanting to do that (that would take place within the function). My intentions are to write the $glue variable only once. Not several times with each concatenation.

Answer 1

$a="hi";
$b = " world";
echo $a.$b;

Answer 2

you can use join or implode, both do same thing and as you say it needs to be an array which is not difficult

join($glue, array($va1, $var2, $var3));

Answer 3

You'll have to use the dot "." operator. This comes from abstract algebra theory, the strings being a monoid with respect to the concatenation operator, and the fact that when dealing with algebraic structures the dot is usually used as a generic operator (the other being "+", which you may have seen used in other languages).

For quick reference, being a monoid implies associativity of the operation, and that there exists an identity element (the empty string, in our case).

Answer 4

Try this:

function join_strings($glue, $arg){
   $args = func_get_args();
   $result = "";
   $argcount = count($args)
   for($i = 1; $i < $argcount; $i++){
       $result .= $args[$i];
       if($i+1!=count($args){
           $result .= $glue;
       }
   }
   return $result;
}

EDIT: Improved function thanks to comment suggestion

Answer 5

You can use func_get_args() to make implode() (or its alias join()) bend to your will:

function join_strings($glue) {
    $args = func_get_args();
    array_shift($args);
    return implode($glue, $args);
}

As the documentation for func_get_args() notes, however:

Returns an array in which each element is a copy of the corresponding member of the current user-defined function's argument list.

So you still end up making an array out of the arguments and then passing it on, except now you're letting PHP take care of that for you.

Do you have a more convincing example than the one in your question to justify not simply using implode() directly?

The only thing you're doing now is saving yourself the trouble to type array() around the variables, but that's actually shorter than the _strings you appended to the function name.

Answer 6

While I agree with the accepted answer, see this article thats says implode is faster than join.