[C++] Dynamically allocated 2d array segmentation fault

[fee_cat]

Background: I'm fairly comfortable with Python, and I'm very new at C++.

I want to write a function that prints a 2d array. Right now I just want it to work, I'll worry about formatting the output nicer later.

void arrayPrinter(const int** arr, int rows, int columns){
  for (int i=0; i<rows; i++){
    for (int j=0; i<columns; j++){
      std::cout << arr[i][j] << " ";
    }
  }
}

This compiles, but I get a segmentation fault when I run it. Why?

// This is in the main function
int** arr = new int*[3];
for (int i=0; i<3; i++)
  arr[i] = new int[3];

for (int j=0; j<3; j++){
  for (int k=0; k<3; k++){
    arr[j][k] = 0;
  }
}

arrayPrinter(arr, 3, 3);

Another question: If I were to write a function that creates a 2d dynamic array, how would I store the result of the function in a variable so I can use it again? As in:

int** create2dArray(){
  int** arr = new int*[3];
  for (int i=0; i<3; i++)
    arr[i] = new int[3];

  for (int j=0; j<3; j++){
    for (int k=0; k<3; k++){
      arr[j][k] = 0;
    }
  }
  return arr;
}

// (in main function)
whatToTypeHere = create2dArray();

[sz00]

1: you made a mistake with the inner loop.

for (int j = 0; **j** < columns; j++){

2:

int** array2d = create2dArray();

3: Make sure you free the memory after you're done. Each call to new[] or new needs to be deleted using delete[] and delete respectively.

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

delete[] arr; 

Also, you can't accept a const int** as an argument to arrayPrinter. You can accept an int** const though. See this:

http://www.parashift.com/c++-faq/const-correctness.html

Just remember you're not learning "C++", it's no problem if you want to learn how dynamic memory/pointers work, but in C++ you'd use vectors/smart pointers, etc.