CODEWITHSUNDEEP
c++g++
Anu
Anu

Reputation: 19

g++ 2.9-gnupro-98r2, error: cannot declare references to functions; use pointer to function instead

I am facing a compilation error with one g++ version (2.9-gnupro-98r2)for LynxOS-178B 2.2.2, whereas the same code will be compiled without complaints with a newer version of g++, e.g. 4.3.3 for VxWorks 653 2.4.0.2.

The following example illustrates the problem:

int method1(int);

void RefInit(){

    int (&rmethod) (int) = method1;
    rmethod(5);

    return;
}


int method1(int x){

    int y = x = 10;
    return y;
}

At line int (&rmethod) (int) = method1; for 2.9-gnupro-98r2 I am getting:

../../src/Overloading_13_3_1_6_Initialization_by_conversion_function_for_direct_
reference_binding.cpp(8) : error: cannot declare references to functions; use pointer to function instead

If one compiler version accepts the code it cannot be completely wrong. My guess is that it conforms to the C++ standard, but the older compiler was lacking a proper implementation of the same.

  1. What exactly is the problem?
  2. Is there a portable way of writing that kind of code such that as much compilers as possible accept it

Upvotes: 0

Views: 114

Answers (1)

Majora320
Majora320

Reputation: 1351

The problem is exactly what was said in the error message.

To solve it, use a pointer to the function:

int method1(int);

void PtrInit(){

    int (*rmethod) (int) = &method1;
    rmethod(5);

    return;
}


int method1(int x){

    int y = x = 10;
    return y;
}

rmethod(5) automaticly converts to (*rmethod)(5).

Upvotes: 1

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