问简单程序因某种原因崩溃

EN

    #include <iostream>
    #include <math.h>
    #include <string>
    #include <conio.h>

    using namespace std;

    void binToDec()
    {
    string bin;
    cout<<"Binary code: ";
    cin>>bin;

    int powr = 0;
    int num = 0;
    long long sum = 0;


    for(int i=bin.size()-1; i>=0; i--)
    {
        if(bin[i] == '1')
        {
            num = 2;
        }
        else if(bin[i] == '0')
        {
            num = 0 ;
        }
        sum += pow(num,powr);
        cout<<sum<<endl;

        powr++;
    }
    cout<<"Decimal: "<<sum<<endl;

    sum = 0;
    powr = 0;
    num = 0;
}

void decToBin()
{
    int dec = 0;
    cout<<"Decimal number or digit: ";
    cin>>dec;

    int i = 0;
    int *numBin = new int[i];
    while(dec > 0)
    {
        numBin[i] = dec%2;
        dec = dec/2;
        i++;
    }
    cout<<"Binary: ";
    for(int j = i-1; j>=0; j--)
    {
        cout<<numBin[j];
    }
    cout<<"\n";
    i = 0;
    delete [] numBin;
}

int main()
{
    //USER INPUT
    int nav = 0;


    while(true)
    {
        cout<<"\n";
        cout << "1.Binary to decimal:"<<endl;
        cout << "2.Decimal to binary:"<<endl;
        cin>>nav;

        switch(nav)
        {
        case 1:
        {
            binToDec();
            break;
        }
        case 2:
        {
            decToBin();
            break;
        }
        }

    }
    return 0;
}