C++: Function Pointer assignment cannot convert types

Alex94102

I am having issues properly declaring and using function pointers to functions defined inside a class:

all works fine for use case outside a class, for example:

typedef bool (*FunctionPointerType1)(int&);
bool functionImplementation1(int& a) {
    a++;    // Just increments the parameter
}
FunctionPointerType1 getFunctionPointer1() {
    return functionImplementation1;
}
int main(int argc, char *argv[])
{
    FunctionPointerType1 imp1 = getFunctionPointer1();

Repeating the same exercise for a function defined inside a class I get to see the issue, why?

class MainClass {
private:
    typedef bool (MainClass::*FunctionPointerType)(int&);
    bool functionImplementation(int& a) {
    a++;    // Just increments the parameter
}
FunctionPointerType getFunctionPointer() {
    return functionImplementation;
    /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^
        error: cannot convert 'MainClass::functionImplementation' from type 'bool (MainClass::)(int&)' to type 'MainClass::FunctionPointerType {aka bool (MainClass::*)(int&)}'
    */
}
public:

koahnig

@Alex94102

I think this should be:

  typedef bool (MainClass::*FunctionPointerType)(int&);

Alex94102

Yes thanks, the post did't render the correctly, I re-posted that. That's exactly how it was to start with.

kshegunov

@Alex94102

FunctionPointerType getFunctionPointer()
{
    return &MainClass::functionImplementation;
}

?

Alex94102

**I want to cry! Thank you soooooo much! I really appreciated your help. **

kshegunov