How to compare whole 2D array rows not elements

Question

For a function of the form.

bool contains_equal_rows(int height, int width, const int ar[height][width])

How do I find if a row is repeated? I can see how you can set a bool to true if a row is repeated, but how do you avoid returning false too early?

Problem description:

Write a function that gets a 2-d array of given dimensions of ints.
It returns true if the array contains two rows with exactly the same values in the same order, and returns false otherwise.

bool contains_equal_rows( int height, int width, const int ar[height][width])

Examples:

On input

{{1,2,3,4},
{2,3,4,1},
{1,2,3,4}}

it returns true.

On input

{{1,2,3,4},
{2,3,4,5},
{3,4,5,6}}

it returns false.

On input

{{1,1,1,1},
{2,2,2,2},
{1,1,1,6}}

it returns false.

My attempt so far:

bool contains_equal_rows(int height, int width, const int array[height][width])
{
  int w = width;
  int h = height;
  bool test = false;
  bool matchedRow = false;

  for(int m = 0; m < h; m++)
  {
    for(int n = 0; n < w; n++)
    {
        if( array[m][n] == array[m][n-1] )
        {
            test = true;
        }
        else
        {
            test = false;
        }
    }

    if(test == true)
    {
        matchedRow = true;
    }
  }
  return matchedRow;
}

The problem with my code is that I'm only comparing a row with the one before it, and can't figure out how to compare one row with all.

Expected results as shown in description.

Answer 1

You should start your outer loop from 1.
And in your inner loop compare array[0] against array[m],
before entering into the inner most loop set test to false
as soon as test is true you can break out of both loops and return true.

Answer 2

You could add another for-loop:

For each row `i`:  
    For every other row `j`:  
        For each column `k` compare `array[i][k]` and `array[j][k]`   

Something like this for example:

int w = width;
int h = height;
boolean test = false;

for(int i = 0; i < h; i++)
{
    for(int j = i+1; j < h; j++) {
        test = true;
        for(int k = 0; k < w; k++)
        {
            if( array[i][k] != array[j][k] )
            {
                test = false;
            }
        }
        if(test == true)
        {
            return true;
        }
    }
}
return false;