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.

bumperbox · Accepted Answer · 2009-07-19 21:31:36Z

21

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));

answered Jul 19, 2009 at 21:31

bumperbox

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7 Comments

hbw Over a year ago

This is the way I'd do it, personally.

Sampson Over a year ago

I had thought about this (as noted in my question), but was wondering if there are already options that allow me to immediately add my strings rather than creating an array, and then adding strings.

Sampson Over a year ago

I'm upvoting even though it's not the answer I am looking for. This is definitely a fast solution, that is both clean and elegant. It may be my fall-back.

Pascal MARTIN Over a year ago

I probably would do it this way too

Etzeitet Over a year ago

You could have your custom string_join function add the strings to an array for you. All you would have to do is pass the individual strings as arguments.

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mercator · Accepted Answer · 2009-07-19 22:20:27Z

8

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.

edited Jul 19, 2009 at 22:20

answered Jul 19, 2009 at 21:58

mercator

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1 Comment

Sampson Over a year ago

+1 for an excellent contribution and for pointing out that an array is impossible to avoid in this case.

luiscubal · Accepted Answer · 2009-10-16 20:29:27Z

3

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

edited Oct 16, 2009 at 20:29

answered Jul 19, 2009 at 21:52

luiscubal

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2 Comments

Sampson Over a year ago

I wrote up a similar function just minutes ago. Plus 1 for arriving to the same conclusion. I am going to go with the accepted-solution using join() instead as it's more parsimonious. Thank you for your involvement.

Miro Solanka Over a year ago

You could make this more efficient by using the "count($args)" only once at the beginning of the function and not in every repetition.

iBiryukov · Accepted Answer · 2009-07-19 21:30:53Z

2

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

answered Jul 19, 2009 at 21:30

iBiryukov

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3 Comments

Sampson Over a year ago

I'm familiar with concatenation. I don't want to have to repeat the $glue over and over, which is why I'm looking for a function.

luiscubal Over a year ago

With some foreach statement, it shouldn't be too hard.

Sampson Over a year ago

foreach would imply an array, which my question said I initially want to avoid :)

Dave Archer · Accepted Answer · 2009-07-20 08:58:36Z

0

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

answered Jul 20, 2009 at 8:58

Dave Archer

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2 Comments

Sampson Over a year ago

Thanks, David. I'll +1 you for that :)

viam0Zah Over a year ago

According to the PHP manual, join is an alias of implode(), see hu.php.net/join

Agos · Accepted Answer · 2009-07-19 21:38:54Z

-1

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).

answered Jul 19, 2009 at 21:38

Agos

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1 Comment

Etzeitet Over a year ago

He doesn't want to use the concatenation operator directly. He was asking if there already existed a function to combine strings to save him the effort of manually coding the concatenation over and over.

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