fredag 26. februar 2016

typedef, structs and function pointers

Just a quick reminder about structs and typedefs in C:


A named struct is created like this:

struct MyStruct{
  int anInt;
}

A custom type like this:

typedef int MyType;


The two syntaxes may be combined like this

typedef struct MyStruct{
  int anInt;
} MyType;


In use you can then either write

void myFunction(struct MyStruct someValue);

or

void myFunction(MyType someValue);


in the latter case omitting the struct keyword.


Function pointers


A variable containing a pointer to a function can be written like this:

returnType (*pointerName)(parameterType)

For example:

void (*myFunctionPointer)(int)


The pointer is then for example assigned like this:

myFunctionPointer = &someFunction;


Combined with typedef you can get:

typedef void (*myFunctionPointerType)(int)

and then use myFunctionPointer as a type:

myFunctionPointer aFunction = &someFunction;

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