Print Vector elements using Boost.Bind - c++

Question

I need to print the values inserted in the vector using Boost.Bind.
Please find the code snippet below:
Please let me know what I am missing here?
class Test
{
int i;
public:
Test() {}
Test(int _i)
{
i = _i;
}
void print()
{
cout << i << ",";
}
};
int main()
{
std::vector<Test> vTest;
Test w1(5);
Test w2(6);
Test w3(7);
vTest.push_back(w1);
vTest.push_back(w2);
vTest.push_back(w3);
std::for_each(vTest.begin(), vTest.end(),boost::bind(boost::mem_fn(&Test::print), _1, ?)); // How do I print Vector elements here?
}

Answer 1

You can do it without boost like this
#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
class Test {
int i;
public:
Test() {
}
Test(int _i) {
i = _i;
}
void print() const {
std::cout << i << std::endl;
}
};
int main() {
std::vector<Test> vTest;
Test w1(5);
Test w2(6);
Test w3(7);
vTest.push_back(w1);
vTest.push_back(w2);
vTest.push_back(w3);
// use lambda
std::for_each(vTest.begin(), vTest.end(), [&](const Test& t){ t.print(); });
// use std::bind
std::for_each(vTest.begin(), vTest.end(), std::bind(&Test::print, std::placeholders::_1));
return 0;
}

Answer 2

Maybe you do not want to have the parameter i for your function print() ? If so, you should simply do like this:
std::for_each(vTest.begin(), vTest.end(),boost::bind(&Test::print, _1));
This will output something like this: 5,6,7,. See live.
If you still want to have some argument passed into your function, then you should pass it to bind():
std::for_each(vTest.begin(), vTest.end(),boost::bind(&Test::print, _1, 0));
0 will be your argument for Test::print(). And, in case of your code, you will have next output: 0,0,0,. See live.
If you fix function to next one:
void print(int i)
{
cout << this->i << " " << i << ",";
}
output will be next: 5 0,6 0,7 0,. See live

Answer 3

You don't need bind there.
Just replace the for_each from your code with the below statement.
std::for_each(vTest.begin(), vTest.end(), std::mem_fn(&Test::print)) ;