How can you pass a vector<pair<int, int> > into a function?

Question

If I try to declare the function as void some_function(vector<pair<int, int> > theVector) , I get an error (presumably from the comma after " pair<int ." Any ideas on how I can pass this vector with pairs into a function?

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <vector>

void someFunc(int x, int y, vector<pair<int, int> > hello);

int main()
{
    int x = 0;
    int y = 5;

    vector<pair<int, int> > helloWorld;
    helloWorld.push_back(make_pair(1,2));

    someFunc(x,y,helloWorld);
}

void someFunc(int x, int y, vector<pair<int, int> > hello)
{
    cout << "I made it." << endl;
}

Error: 'vector' has not been declared

Answer 1

You failed to include <utility> , which defines std::pair , and you're using vector and pair , instead of std::vector and std::pair .

All of the standard template library is inside the namespace std , so you must prefix types from the STL with std , like std::vector . An alternative would be to add using std::vector; after you include <vector> .

Answer 2

You need to have provide full namespace for vector, pair, make_par, they are from std namespace:

void someFunc(int x, int y, std::vector<std::pair<int, int> > hello);

int main()
{
    int x = 0;
    int y = 5;

    std::vector<std::pair<int, int> > helloWorld;
    helloWorld.push_back(std::make_pair(1,2));

    someFunc(x,y,helloWorld);
    return 0;
}

void someFunc(int x, int y, std::vector<std::pair<int, int> > hello)
{
    std::cout << "I made it." << std::endl;
}

Side note: you could pass vector to someFunc by reference, this will elide unnecessary copy:

 void someFunc(int x, int y, const std::vector<std::pair<int, int> >& hello);
                              ^^^                                   ^^

Answer 3

Have you included <vector> and <utility> ? You should use the std:: namespace on both vector and pair .

eg. void some_function(std::vector< std::pair<int, int> > theVector)

edit: Of course you generally shouldn't pass in a vector by value, but by reference.

eg. void some_function(std::vector< std::pair<int, int> >& theVector)

Answer 4

I chekced your code you just have to add the std namespace right below your #include . And you don't need to add #include <utility> it can work without it.
using namespace std

Answer 5

left	center	right
One	Two	Three