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c++lambdastdbind

Lambda functions in C++ strange behaviour

I have the following program where I am trying to print out multiplication table of 10, using a combination of lambda functions and std::bind. The primary purpose is to learn the above two concepts. However the output that I get (given below) is strange.

#include <iostream>
#include <vector>
#include <algorithm>
#include <thread>
#include <zconf.h>
#include <functional>
using namespace std;
using namespace std::placeholders;
int multiply(int a, int b, int c)
{
    return a*b*b;
}
int main()
{
    auto f = std::bind(multiply, 5 , 2 , _1);
    vector<int> vec = {1,2,3,4,5,6,7,8,9,10};
    for_each(vec.begin(), vec.end(), [f](int &v) {cout << "Multiplication Table (10) :" << "v: " << v << " " << f(v) << endl;});
    return 0;
}

Output:

Multiplication Table (10) :v: 1 20
Multiplication Table (10) :v: 2 20
Multiplication Table (10) :v: 3 20
Multiplication Table (10) :v: 4 20
Multiplication Table (10) :v: 5 20
Multiplication Table (10) :v: 6 20
Multiplication Table (10) :v: 7 20
Multiplication Table (10) :v: 8 20
Multiplication Table (10) :v: 9 20
Multiplication Table (10) :v: 10 20

Process finished with exit code 0

What is it in the above code that I am doing wrong. What should be fixed so that it actually prints the multiplication table for 10.

Solution

  • Looks like a simple typo to me. Change

    return a*b*b;

    to

    return a*b*c;