[Resolved] Is there a better way?

[The Hobo]

I just spent forever finding a way to do this:

#include <iostream>
using namespace std;

double *incArray(double *arr);

int main() {
    double *vars;

    for (int i = 0; i < 4; i++) {
        vars = incArray(vars);

        vars[i] = i;
        cout << vars[i] << endl;
    }
    
    cout << endl << "After: " << endl << endl;

    for (i = 0; i < 4; i++) {
        cout << vars[i] << endl;
    }

    return 0;
}

double *incArray(double *arr) {
    
    double *arrtemp = arr;

    arr = new double[sizeof(arr)];

    for (int i = 0; i < sizeof(arrtemp); i++) {
        arr[i] = arrtemp[i];
    }

    return arr;

}

Is that good or is there a better way?

[riis]

What do you want to do? I can't deduct that from the code.
But I think you're doing something wrong in the incArray function. You're taking the size of an unintialized pointer. That doesn't work here. (Although you can except that it will return the value 4).
Besides, if you initialize the size of an array with 'new', you should 'delete' it after usage, in order to free the claimed memory.

[The Hobo]

I'm just trying to create a dynamic array and write a function to increase its size.

[parksie]

Why not use a vector?

[The Hobo]

Is this better?

#include <iostream>
using namespace std;

double *incArray(double *arr);

int main() {
    double *vars;

    vars = new double[1];
    vars[0] = 22;

    for (int i = 1; i < 5; i++) {
        vars = incArray(vars);

        vars[i] = i;
        cout << vars[i] << endl;
    }
    
    cout << endl << "After: " << endl << endl;

    for (i = 0; i < 5; i++) {
        cout << vars[i] << endl;
    }

    return 0;
}

double *incArray(double *arr) {
    
    double *arrtemp = arr;
    arr = new double[sizeof(arr)];

    for (int i = 0; i < sizeof(arrtemp); i++) {
        arr[i] = arrtemp[i];
    }
    
    delete[] arrtemp;

    return arr;

}

I tried also deleting vars in main(), but it gave me a debug error.

[The Hobo]

Originally posted by parksie
Why not use a vector?

because I have no idea what vector is.

[parksie]

Search the forums, but basically, it's a dynamic array. It's fast, and very easy to use.

[The Hobo]

Originally posted by parksie
Search the forums, but basically, it's a dynamic array. It's fast, and very easy to use.

Okay. I'm convinced.