Use 2d Array with diffrent size of 2-nd row C++

Question

Currently i'm tring to do 2d array in c++ that can have diffrent second column size. This is my code:

int **testZadanie;
testZadanie = new int*[testy];
...
for (int i = 0; i<testy; i++)
{
    cin >> liczbaLakomczuchow >> liczbaCiastek;
    testZadanie[i] = new int[liczbaLakomczuchow];
    for (int j = 0; j<liczbaLakomczuchow; j++)
    {
        cin >> czasJedzenia;
        //testZadanie[i, j] = czasJedzenia; this not works
        *testZadanie[i, j] = czasJedzenia;
    }
}

But when I want to attach values for each column i got exception. So i'm not sure if I can do this what i actually trying do ? ( declaring dynamic column element for each row and attach for each item in row ? )

HolyBlackCat · Accepted Answer · 2017-04-08 13:24:27Z

1

Use x[y][z] instead of x[y, z].

When you write *x[y, z], the compiler interprets it as x[z][0] (which is not what you want) because:

a, b is a comma operator, which evaluates both operands and returns the value of the second one.
*a is equivalent to a[0].

_{This answer generally applies to builtin types only. You can overload ,, * and [] operators for a class, changing their behaviour completely.}

_{If you don't know what operator overloading is, just ignore this remark.}

answered Apr 8, 2017 at 13:24

HolyBlackCat

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