Re: Basic c question again - type casting

[James Rich <james@xxxxxxxxxxx>]

On Thu, 12 Jun 2008, Lim Hock-Chai wrote:

> If I've a function like below:
>   void logECD_STP3(const char **dataRcv);

What you have above is a function that accepts a pointer to a pointer to a 
char.

> Below compile and work fine:
> char * data;
> // code that put stuff into data
> . . .
> logECD_STP(&data);

This works because the declaration

char * data;

defines a pointer to a char.  the & symbol means "the address of", so 
"&data" means "the address of the variable data".  Pointers are merely 
addresses, so since data is a pointer, &data is a pointer to a pointer 
(i.e. & is the address of where a pointer is stored, or & points to data 
which points to something else).

> How do I do the same thing if I've
> UAM * data;

Above you have declared a pointer that points to a variable of type UAM.

> // code that put stuff into data
> . . .
> logECD_STP(&data);   <== I got a compile error Function argument
> assignment between types "unsigned char* const*" and "struct
> uasmgfile**"

You get this error because logECD_STP() accepts pointers to pointers of 
type char, not pointers to pointers of type UAM.

James Rich

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