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C ++ static method with struct parameters

I have this problem ...

I have my structure:

typedef struct Mystruct{
  float a;
  float b;
}

and a static method:

float static MyStaticMethod(MyStruct a, MyStruct b);

when i call this method:

Mystruct s;
s.a = 1;
s.b = 2;

Mystruct t;
t.a = 1;
t.b = 2;

MyClass.MyStaticMethod(s,t);

I have this compile-time error:

Error   51  error C2228: left of '.MyStaticMethod' must have class/struct/union

Error   50  error C2275: 'MyClass' : illegal use of this type as an expression
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3 answers


You need to call it using the scope resolution operator:



MyClass::MyStaticMethod(s,t);
       ^^
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besides using "MyClass :: MyStaticMethod (s, t);", you can also call a static method on an instance:

MyClass instance;
instance.MyStaticMethod(s,t);

and it should read:



typedef struct {
  float a;
  float b;
} Mystruct;

(new name starts last)

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The keyword is static

overloaded in C ++ (i.e. has multiple meanings). In the code you presented:

struct MyStruct {
};
static float MyStaticFunction( MyStruct, MyStruct );

the value static

is an internal linkage (i.e. the character will not be used outside the current translation unit. If this is present in the header, then each includes a translation unit which will receive its own copy of the function. in this case the free function function is used :

MyStruct a,b;
float f = MyStaticFunction( a, b );

It seems from trying to use it what you meant was using static

in this alternate scenario:

struct MyStruct {
   static float MyStaticFunction( MyStruct, MyStruct );
};

where it has a different meaning: the member belongs to the class, not a specific instance. In this case, the function can be called in one of two ways, the most common being:

MyStruct a,b;
float f = MyStruct::MyStaticFunction( a, b );

although the language also allows (I would not recommend using it, it can be confusing):

float f a.MyStaticFunction(a,b);

If confusion arises because it is like calling a member function on a

rather than calling a static member function in a class.

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