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What are these expressions ?

What are these expressions ?

What are these expressions ?

I am just returning to C programming after a few years absence.  Would appreciate your comments on the following two expressions which were passed as arguments in a function call:

(coordinate_set_t * )NULL,
(Line_t  **) new_obj

Are the expressions in parentheses  casts and was the type being casted defined in a typedef somewhere? Is it legal in ansi C to use a new type created in a typedef statement as a cast?  Unfortunately this is part of a very large system and I have not yet found the prototype for the function and its arguments.  Thanks.

RE: What are these expressions ?

Yes, that's a cast, and it looks like it is defined in a typdef. I'm reasonably sure that Ansi C allows casts to typedefs, since a typedef is really just a synonym of sorts.

Can't you just do a quick search through all the source files to find the definitions?


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