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Question on return_value

php.internals

Bob Silva

20 years ago

Hi,

I have an internal function defined that returns an array zval:

zval *pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
TSRMLS_DC);

When I call it like this,  return_value is NULL in userland.

return_value = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator,
count, 0 TSRMLS_CC);

But when I call it like this, it works as expected and an array is returned
to userland

array = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
TSRMLS_CC);

*return_value = *array;

I'm sure there is an obvious answer, but given my background (or lack
thereof) in C, I can't figure it out.

How does the temporary assignment change things inside the engine?

Bob

Michael Wallner

20 years ago

Bob Silva wrote:

> Hi,
>
> I have an internal function defined that returns an array zval:
> zval *pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
> TSRMLS_DC);
>
>
> When I call it like this,  return_value is NULL in userland.
>
> return_value = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator,
> count, 0 TSRMLS_CC);

The outta world doesn't care if you let return_value point else where in
your function.  Look up the chapter pointers in your book. Short version:
You need a pointer to a pointer so that the caller gets another pointer.

> But when I call it like this, it works as expected and an array is returned
> to userland
>
> array = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
> TSRMLS_CC);
>
> *return_value = *array;

Yes, because you change the members of the struct the pointer points at and
the pointer is still the same of that of the "outta world".

> I'm sure there is an obvious answer, but given my background (or lack
> thereof) in C, I can't figure it out.
>
> How does the temporary assignment change things inside the engine?

Hä? :)

Regards,

--
Michael - <mike(@)php.net> http://dev.iworks.at/ext-http/http-functions.html.gz

Marcus Börger

20 years ago

Hello Bob,

look at RETURN_ZVAL() again.

Tuesday, November 1, 2005, 7:47:45 AM, you wrote:

> Hi,

>

> I have an internal function defined that returns an array zval:

>

> zval *pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
> TSRMLS_DC);

>

>

>

> When I call it like this,  return_value is NULL in userland.

> return_value = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator,
> count, 0 TSRMLS_CC);

>

>

> But when I call it like this, it works as expected and an array is returned
> to userland

> array = pow_zstring_internal_split(Z_STRVAL_P(ivalue), separator, count, 0
> TSRMLS_CC);

> *return_value = *array;

>

>

> I'm sure there is an obvious answer, but given my background (or lack
> thereof) in C, I can't figure it out.

> How does the temporary assignment change things inside the engine?

>

> Bob

Best regards,
Marcus