C++ Passing a class method as function pointer - c++

Question

I have a class that has to process data from various files. I thought about creating one function that will read the specified file and then also accept a call back so that it can use that to process the line. Below is an example class to represent what I am trying to do:
#include <iostream>
#include <vector>
#include <string>
class Example
{
std::vector<std::string> m_exampleFileData {
"test1",
"test2",
"test3"
};
public:
void doSomethingMain(const std::string& path)
{
processFile(path, doSomething);
}
private:
void processFile(const std::string& filePath, void (Example::*fpProcessLine)(const std::string&) )
{
for (const auto& line : m_exampleFileData) {
this->*fpProcessLine(line);
}
}
void doSomething(const std::string& line)
{
std::cout << "Hello: " << line << '\n';
}
};
int main(int argc, char** argv) {
const std::string filePath{"path"};
Example ex;
ex.doSomethingMain(filePath);
}
Compiler explorer: https://godbolt.org/z/LKoXSZ
The main issue is that no matter what I do I can't seem to be able to pass the function properly to processFile. Is there a way to do this in C++? How do I go about this?

Answer 1

You need to spell things out explicitly, in this situation:
processFile(path, &Example::doSomething);
Furthermore, you also need to slap on an extra pair of parenthesis, due to operator precedence:
(this->*fpProcessLine)(line);