extern pointer C bug or not?

The question is not clear enough.

You'd better show a simple example.

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originally posted by david_cai@Oct 24 2006, 07:16 PM

the question is not clear enough.

you'd better show a simple example.

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=18886)

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Example:

// in declaration file

cyg_uint8 gr_data_written[5] = {1,2,3,4,5};

---

// in this other file# ifdef FIRSTWAY

extern cyg_uint8 gr_data_written[];# else

extern cyg_uint8 *gr_data_written;# endif

showme()

{

printf ("%x", (int) gr_data_written);

# ifdef FIRSTWAY

output of printf is a ptr "4A178";# else

output of printf is the value "1";# endif

-----------

I thought it was supposed to be the same either way, but it wasn&#39;t.

I think it is related to declaring a pointer vs. declaring an array.

Note, the *gr_data_written pointer is not declared anywhere nor initialized.

Thus, the result should be undefined.

When declaring, pointer and array are different.

Garland

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originally posted by itntest+oct 26 2006, 05:23 pm--><div class='quotetop'>quote (itntest @ oct 26 2006, 05:23 pm)</div>

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<!--quotebegin-david_cai@Oct 24 2006, 07:16 PM

the question is not clear enough.

you&#39;d better show a simple example.

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=18886)

--- quote end ---

--- Quote End ---

Example:

// in declaration file

cyg_uint8 gr_data_written[5] = {1,2,3,4,5};

---

// in this other file# ifdef FIRSTWAY

extern cyg_uint8 gr_data_written[];# else

extern cyg_uint8 *gr_data_written;# endif

showme()

{

printf ("%x", (int) gr_data_written);

# ifdef FIRSTWAY

output of printf is a ptr "4A178";# else

output of printf is the value "1";# endif

-----------

I thought it was supposed to be the same either way, but it wasn&#39;t.

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=18938)</div>

[/b]

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Not convinced yet.

Thoughts from anyone else?

Please try the following.

<span style="font-family:Courier">// in declaration file

cyg_uint8 gr_data_written[5] = {1,2,3,4,5};

cyg_uint8 *pData = gr_data_written; // initialize the pointer

//---

// in this other file

extern cyg_uint8 gr_data_written[]; // good

extern cyg_uint8 *pData ; // good

</span>

Good luck!

Garland