Triple pointers in C: is it a matter of style?

Question

I feel like triple pointers in C are looked at as \"bad\". For me, it makes sense to use them at times.

Starting from the basics, the single pointer

Answer 1

So what are some of the conventions out there? Is this really just a question of style/readability combined with the fact that many people have a hard time wrapping their heads around pointers?

Multiple indirection is not bad style, nor black magic, and if you're dealing with high-dimension data then you're going to be dealing with high levels of indirection; if you're really dealing with a pointer to a pointer to a pointer to T, then don't be afraid to write T ***p;. Don't hide pointers behind typedefs unless whoever is using the type doesn't have to worry about its "pointer-ness". For example, if you're providing the type as a "handle" that gets passed around in an API, such as:

typedef ... *Handle;

Handle h = NewHandle();
DoSomethingWith( h, some_data );
DoSomethingElseWith( h, more_data );
ReleaseHandle( h );

then sure, typedef away. But if h is ever meant to be dereferenced, such as

printf( "Handle value is %d\n", *h );

then don't typedef it. If your user has to know that h is a pointer to int¹ in order to use it properly, then that information should not be hidden behind a typedef.

I will say that in my experience I haven't had to deal with higher levels of indirection; triple indirection has been the highest, and I haven't had to use it more than a couple of times. If you regularly find yourself dealing with >3-dimensional data, then you'll see high levels of indirection, but if you understand how pointer expressions and indirection work it shouldn't be an issue.

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^{1. Or a pointer to pointer to int, or pointer to pointer to pointer to pointer to struct grdlphmp, or whatever.}