Passing by reference better than returning a value when calling a function?

[duzhidian]

Hello:

When I need a function to generate a string, I have two methods:

1.
pass by reference:

mystring = "";
myfunction( mystring ); // prototype of myfunction( &anystring );

OR 2.
mystring = myfunction(); //which return a string

According to experience of C/C++, the former one is better as of the
efficient, how about PHP?

Thanks.

[Rik Wasmus]

On Sun, 28 Oct 2007 19:25:38 +0100, du*******@gmail.com
<du*******@gmail.comwrote:

Hello:

When I need a function to generate a string, I have two methods:

1.
pass by reference:

mystring = "";
myfunction( mystring ); // prototype of myfunction( &anystring );

OR 2.
mystring = myfunction(); //which return a string

According to experience of C/C++, the former one is better as of the
efficient, how about PHP?

The PHP engine is usually smarter then you think, so efficiency wise there
will be very little difference (you can test this offcourse examining time
& memory usage). From a logical standpoint though, it makes very little
sense to create a _new_ string in an existing variable by reference. I'd
say functions taking arguments by reference only make sense when they
either alter data directly related to their 'previous' value, or store the
values in come other scope.
--
Rik Wasmus

[Michael Fesser]

..oO(du*******@gmail.com)

>When I need a function to generate a string, I have two methods:

1.
pass by reference:

mystring = "";
myfunction( mystring ); // prototype of myfunction( &anystring );

OR 2.
mystring = myfunction(); //which return a string

According to experience of C/C++, the former one is better as of the
efficient, how about PHP?

PHP is not C/C++. Don't compare C's references or pointers with
references in PHP.

If you really have a use for references, then use them. But in all other
cases just use what makes more sense in the application context. Usually
I prefer to have a function return its result, since this allows to
easily nest function calls. The code is more readable (at least for me).

Actually I think that in my own framework there's currently not a single
function that requires arguments passed by reference. Some functions use
references internally, for example for traversing through an array tree,
but in most if not all functions arguments are passed by value.

Micha

[ZeldorBlat]

On Oct 28, 2:25 pm, "[e-mail]" <[e-mail]:

Hello:

When I need a function to generate a string, I have two methods:

1.
pass by reference:

mystring = "";
myfunction( mystring ); // prototype of myfunction( &anystring );

OR 2.
mystring = myfunction(); //which return a string

According to experience of C/C++, the former one is better as of the
efficient, how about PHP?

Thanks.

In addition to what everyone else said (and they're both absolutely
correct) I tried both ways through a profiler. Assigning the return
value was about 40% faster than passing the reference.

So, to reiterate, do what makes sense, not what you /think/ will be
faster. If you run into performance problems later then you can
systematically optimize using a profiler or similar tool.

Google for "premature optimization" for more on the subject.