Access an undeclared struct?

Question

I there a way to access a struct that has not been declared yet?

//Need to some how declare 'monitor' up here, with out moving 'monitor' above 'device'
//because both structs need to be able to access each others members

struct{
    int ID = 10;
    int Get__Monitor__ID(){
        return monitor.ID; //obvioulsly 'monitor' is not declared yet, therefore throws error and is not accessible
    }
} device;

struct{
    int ID = 6;
    int Get__Device__ID(){
        return device.ID; //because 'device' is declared above this struct, the ID member is accessible
    }
} monitor;

Do not tag C for C++ questions. (I presume your code is C++ since C does not provide for function definitions inside structures.) — Eric Postpischil, Feb 13 '21 at 23:19
Does this answer your question? [Separating class code into a header and cpp file](https://stackoverflow.com/questions/9579930/separating-class-code-into-a-header-and-cpp-file) — 273K, Feb 13 '21 at 23:22
This design is suspicious. Both classes assumes that they works with a single object of the other type. As soon as the application has 2 monitors or 2 devices, the design is broken. — Phil1970, Feb 13 '21 at 23:30
`Get__Monitor__ID` That identifier is reserved for the language implementation. You should use another function name. — eerorika, Feb 14 '21 at 01:47

score 5 · Accepted Answer · answered Feb 13 '21 at 23:21

5

In this particular case, you can define the function prototype in the struct, and the definition can come later.

struct device_t {
    int ID = 10;
    int Get__Monitor__ID();
} device;

struct monitor_t {
    int ID = 6;
    int Get__Device__ID();
} monitor;

int device_t::Get__Monitor__ID() {
  return monitor.ID;
}

int monitor_t::Get__Device__ID() {
  return device.ID;
}

answered Feb 13 '21 at 23:21

Bill Lynch

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3

You probably want to add `inline` unless the functions are moved to CPP file. And only first fonction need to be modified. – Phil1970 Feb 13 '21 at 23:24

Access an undeclared struct?

1 Answers1