CODEWITHSUNDEEP
c
swoosh
swoosh

Reputation: 657

confusing C syntax

I am reviewing some C code, but having a hard time understanding what Callback is exactly. Does anyone know what this means? I'm guessing that it is defining "Callback and x to be both a void *?

typedef void (*Callback)(bool x);

Upvotes: 1

Views: 166

Answers (2)

cnicutar
cnicutar

Reputation: 182734

It makes a new type name Callback. Every Callback will be a pointer to a function taking a bool and returning void. In effect Callback will be an alias for that real type. So when you say:

Callback ptr = some_fun;

You're making a function pointer that points at some_fun. Function pointers are typically passed to other functions as arguments.

Upvotes: 5

Alok Save
Alok Save

Reputation: 206616

It declares a function pointer type by the name Callback which points to a function which takes a bool input parameter and returns a void.
Once you specify the statement, You can use Callback as a type to hold address of a function with the specifed type.

Refer the Clockwise spiral rule when in doubt.

Upvotes: 2

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