const arrays in prototypes

[Benjamin Zhu]

In article <1990May26.164834.4211 at jarvis.csri.toronto.edu> norvell at csri.toronto.edu (Theo Norvell) writes:
>In article <1356 at crabcake> zhu at crabcake.cs.jhu.edu (Benjamin Zhu) writes:
>>In article <2781 at sunset.MATH.UCLA.EDU> pmontgom at euphemia.math.ucla.edu (Peter Montgomery) writes:
>>>	Suppose instead that I am passing an array argument.  If I 
>>>put "const" before the declaration, then I am stating that the data 
>>>will not be modified.  How do I specify that the pointer to the array
>>>will not be altered within the subroutine?
>> 
>>	Use the following prototype instead:
>>
>>	void DISALLOW(const int ** const mat)
>>
>>	It's fairly self-explanatory. Add const before mat, indicating that
>>	the pointer is also constant.
>>
>>Benjamin Zhu
>
>Perhaps you mean
>	void DISALLOW( const int (*const mat)[2] )
>But this is UGLY.
>

	OK, this one would work, though someone might think it is ugly.

>Is the following a solution?
>	typedef const int const_matrix[2][2] ;
>	...
>	void DISALLOW( const const_matrix mat )
>If not, I'm sure someone will point out why.
>
	Nope. In this case, "const" has been used twice, i.e., it
	is duplicatedly declared, which I believe is illegal in
	Ansi stardard.  Moreover, I fail to notice any semantical
	difference between "const_matrix" and "const const_matrix".
	Maybe you mean something else?

>Theo Norvell

Benjamin Zhu

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