I would like to print a vector backwards, so I've created a function called reverse. The output is correct but I get this warning message:

Implicit conversion loses integer precision: 'std::__1::vector<int, std::__1::allocator<int> >::size_type' (aka 'unsigned long') to 'unsigned int'

I get this message from the for loop inside the reverseVector function.
Why?

This is my code:

#include <iostream>

#include <vector>



using namespace std;



// functions prototype:

void fillVector(vector<int>&);

void reverseVector(const vector<int>&);



int main(){



    vector<int> myVector;

    fillVector(myVector);

    printVector(myVector);

    reverseVector(myVector);



    return 0;

}



//function definitions

void fillVector(vector<int>& newMyVector){

    cout << "Type in a list of numbers (-1 to stop): ";

    int input;

    cin  >> input;



    while (input != -1) {

       newMyVector.push_back(input);

       cin >> input;

    }

    cout << endl;

 }



void reverseVector(const vector<int>& newMyVector){

    for (unsigned int k = newMyVector.size(); k > 0 ; k = k - 1) {

        cout << newMyVector[k - 1] << " ";

    }

    cout << endl;

}

Avoid using namespace std

It's harmful to include all identifiers from namespaces that are not designed for it. Use just what you need, where you need it - in most cases, it's easier to fully qualify the names you use.

Iterators can be easier than indexing

Instead of

// bug fixed (was: unsigned int k)

for (auto k = newMyVector.size();  k > 0;  k = k - 1) {

    std::cout << newMyVector[k - 1] << " ";

}

look at the iterator equivalent:

for (auto it = newMyVector.rbegin();  it != newMyVector.rend();  ++it) {

    std::cout << *it << " ";

}

There's almost no arithmetic to get wrong here. It would be clearer still with a shorter name for the vector.

Consider allowing other streams

At the moment, we always use the standard input and output streams. What would you need to do, to allow your program to read and write from/to other streams (such as file streams)?