PHP string concatenation using ","?

Question

I just discovered something.

echo $var1 , " and " , $var2;

is the same as:

echo $var1 . " and " . $var2;

What is the actual string concatenation operator in php? Should I be using . or ,?

omg.. u r right? This question is too stupid (duh, I am the stupid question-er).. i will choose the one that has highest vote. Thanks guys(its really hard for me to choose the best answer, I just refresh this page, and I got lots of answers z_z)!! — bbtang, Sep 29 '09 at 08:24

score 14 · Accepted Answer · answered Sep 29 '09 at 08:17

14

The . operator is the concatenation operator. Your first example only works because the echo 'function' (technically it's a language construct, but lets not split hairs) accepts more than one parameter, and will print each one.

So your first example is calling echo with more than one parameter, and they are all being printed, vs. the second example where all the strings are being concatentated and that one big string is being printed.

answered Sep 29 '09 at 08:17

Matthew Scharley

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One more note. `echo` does not take multiple arguments if you call it using parens. This won't work: `echo($a, $b);` – Ionuț G. Stan Sep 29 '09 at 08:25
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I read somewhere that echo "a", "b"; is faster than echo "a"."b"; – Kamil Szot Sep 29 '09 at 10:16
I doubt it's noticably faster, except perhaps for very large 'a' and 'b'. I do believe it though. – Matthew Scharley Sep 29 '09 at 11:01

score 4 · Answer 2 · answered Sep 29 '09 at 08:16

The actual concatenation is . (period). Using , (comma) there, you are passing multiple arguments to the echo function. (Actually, echo is not a function but a PHP language construct, which means you can omit the parentheses around the argument list that are required for actual function calls.)

score 3 · Answer 3 · answered Sep 29 '09 at 08:17

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In the first case you just echo 3 different strings.

In the second case you concatenate the 3 strings and then echo the output.

So the answer is that, in order to concatenate strings you should use the dot (.)

answered Sep 29 '09 at 08:17

Anax

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score 2 · Answer 4 · answered Sep 29 '09 at 08:16

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".". The other just writes several values independently, without actually concatenating the string.
See also PHP echo reference, the "," variant will only work with methods accepting multiple parameters.

answered Sep 29 '09 at 08:16

Lucero

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score 2 · Answer 5 · edited May 23 '17 at 10:27

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"." concatenates, "," can only be used for echo which is a language construct (sort of a function)

also see: Difference between period and comma?

edited May 23 '17 at 10:27

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answered Sep 29 '09 at 08:16

knittl

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score 1 · Answer 6 · edited May 23 '17 at 11:55

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Using a comma doesn't actually concatenate the strings.

See this answer to another question.

edited May 23 '17 at 11:55

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answered Sep 29 '09 at 08:18

kkyy

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score 1 · Answer 7 · answered Sep 29 '09 at 08:18

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The "." is the correct concatenate operator. "echo" also accepts ",", treating it as if you are passing in a series of arguments to the "echo" method and then echoing each one. It's not truly concatenating the strings.

answered Sep 29 '09 at 08:18

Mike A.

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score 0 · Answer 8 · answered Sep 29 '09 at 08:17

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nop it's because echo could take more then one argument, it would do the print each arguments

answered Sep 29 '09 at 08:17

RageZ

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I doubt echo does a concatentation, it just prints each parameter. – Matthew Scharley Sep 29 '09 at 08:18
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yeah but happens to have the same effect. – RageZ Sep 29 '09 at 08:19

PHP string concatenation using ","?

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