PHP string operations [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

Why is the php string concatenation operator a dot (.)?

I've always wondered -

Why does PHP use the 开发者_运维技巧. operator to concat strings instead of the + sign?

Is this some sort of way to improve script-evaluation performance?

Thanks

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Because otherwise, what would happen in this case?

$str = "4";
$num = 2;

$result = $str + $num;

What if you wanted the result to be "42"?

Clarification

The above answers the question "why is there an operator . in addition to the operator +?". If the intended question was "why does operator + not perform string concatenation?" (with the understanding that the would need to be another operator to take over the current behavior +), then I 'll be happy to remove my answer in favor of a more relevant one.

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After deciding that it (PHP) would do lots of autoboxing there was pretty much no other choice then to use 2 different operators for "adding" and "concating".

"+" for adding is obvious and @Gumbo explained why "." was chosen.

var_dump("12ab" + "34cd"); // 46
var_dump("12ab" . "34cd"); // "12ab34cd"

so you need to tell the language that you want it to do because it can do both :)

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Other languages don't have that problem because they don't allow the implicit conversion from a string to an integer.

So if you write "4" + 2 the language would tell you that it can't to that and you'd need to write: intval("4") + 2 and it knows what to do.

Also see here

why-is-the-php-string-concatenation-operator-a-dot

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Because Perl used the . for string concatenation and PHP was highly influenced by Perl’s syntax.