Insertion sort

Code:

---

#include <iostream>
#include <vector>
using namespace std;
template <typename T>
void insertionSort(vector<T> &v1);
int main()
{   
    const int SIZE = 5;
    int myArray[SIZE] = {5,3,2,4,1};
    vector<int> vect(myArray, myArray+5);
    insertionSort(vect);

    for(int i=0; i<SIZE; i++)
    {
        cout<< vect[i] << " ";
    }
    cout<<endl;

    return 0;
}

void insertionSort(vector<int> &v1)
{
    int i;
    int j;
    int temp;
   
    for(i = 1; i < v1.size(); i++)
    {
        j=i;
        while(j>0 && v1[j-1] > v1[j])
        {
            temp = v1[j-1];
            v1[j-1] = v1[j];
            v1[j] = temp;
            j--;
        }
    }
}

---

The code is runs properly, but for some reason it's getting an error that says "insertion sort\test.cpp(29): warning C4018: '<' : signed/unsigned mismatch" What does that mean?

vector::size does not return an int. You should give your loop counter type std::size_t which would be what the function returns. This will eliminate your warnings.
The warnings comes from that std::size_t is an unsigned type (cannot contain negative numbers) while "i" is a signed type (can contain negative numbers). When comparing a signed and an unsigned type of the same size, you get this warning.

In the c++ program language, when you compare the sign int with the unsigned int ,the compiler will convert the "sign int " to "unsigned int". so the negative integer will be converted to nonegative, this is very dangeous. the warning is this mean.