CODEWITHSUNDEEP
c++11c++14
user9452578
user9452578

Reputation:

C++ swapping function

Why doesn't my function influence the original vector I passed in main()?

void swap2(int &x, int &y)
{
    int temp = x;
    x = y;
    y = temp;

}

void reverse_2(vector<int> &v1)
{
    int j = v1.size() - 1;
    cout << j << endl;
    for (int i = 0; i != v1.size(); ++i)
    {
        swap2(v1[i], v1[j]);
        j--;
    }
}

int main()
{
    vector<int>i1 = { 1,3,5,7,9 }, i2(i1.size());
    i2 = reverse_1(i1);
    for (int i = 0; i != i1.size(); ++i)
    {
        //cout << "First array"<<i1[i] << ","<<endl;
        //cout << "Second array" << i2[i] << "," << endl;
    }
    reverse_2(i1);
    cout << "First array changed" << endl;
    for (int i = 0; i != i1.size(); ++i)
        cout << i1[i] << ",";
    cout << endl;
    return 0;
}

Upvotes: 0

Views: 59

Answers (1)

Matthieu Brucher
Matthieu Brucher

Reputation: 22023

You are inverting every element in your vector twice.

The first time you put say 0 to n-1, then when you hit i=n-1, you swap them back...

for (int i = 0; i < i1.size() / 2; ++i)

Upvotes: 1

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