User Defined Types Passing to a Function is a Call By Value in C?

I have a struct and I pass开发者_开发问答 this struct to function. Maybe function protype is:

typedef struct
{
    //Bla Bla
} ABC;

void func(ABC abc)
{

}

This function calling is Call by value or Call by referance? Someone say that "C doesnt have Copy Constructor so we cant pass user defined types with value". Is this idea correct?

Call by value. C is always call by value.

(C doesn't have copy constructors but structures can still be copied by creating a second structure with the original structure as its initializer. Function parameters are initialized with the values that you pass as arguments; it's the same mechanism at work.)