When i run this code below, errors pop out error: like subscripted value is not an array, pointer, or vector edgeimage[i][j] = image[height][width];

Question

void edges(int height, int width, RGBTRIPLE image[height][width])
{
//Set temp image
RGBTRIPLE *edgeimage = malloc((height + 1) * (width + 1) + 4);

//RGBTRIPLE 
edgeimage[height][width];

//Go through all pixels and copy to edgeimage
for (int i = 0; i < height; i++)
{
    for (int j = 0; j < width; j++)
    {
        edgeimage[i][j] = image[i][j];
    }
}

for (int i = 0; i < height; i++)
{
    for (int j = 0; j < width; j++)
    {
        int Gx[3][3] = { {-1, 0, 1},
                         {-2, 0, 2},
                         {-1, 0, 1} };
                         
        int Gy[3][3] = { {-1, -2, -1},
                         {0 , 0 , 0 },
                         {1 , 2 , 1 } };
        
        int GxRed = 0, GxGreen = 0, GxBlue = 0, GyRed = 0, GyGreen = 0, GyBlue = 0;
        
        for (int k = -1; k < 2; k++)
        {
            if (i + k < 0 || (i + k > height - 1))
            {
                edgeimage[i + k][j].rgbtRed = 0;
                edgeimage[i + k][j].rgbtGreen = 0;
                edgeimage[i + k][j].rgbtBlue = 0;
            }
            for (int h = -1; h < 2; h++)
            {
                if (j + h < 0 || (j + h > width - 1))
                {
                    //continue;
                    edgeimage[i][j + h].rgbtRed = 0;
                    edgeimage[i][j + h].rgbtGreen = 0;
                    edgeimage[i][j + h].rgbtBlue = 0;
                }
                for (int a = 0; a < 3; a++)
                {
                    for (int b = 0; b < 3; b++)
                    {
                        GxRed += edgeimage[i + k][j + h].rgbtRed * Gx[a][b];
                        GxGreen += edgeimage[i + k][j + h].rgbtGreen * Gx[a][b];
                        GxBlue += edgeimage[i + k][j + h].rgbtBlue * Gx[a][b];
                        
                        GyRed += edgeimage[i + k][j + h].rgbtRed * Gy[a][b];
                        GyGreen += edgeimage[i + k][j + h].rgbtGreen * Gy[a][b];
                        GyBlue += edgeimage[i + k][j + h].rgbtBlue * Gy[a][b];
                    }
                }
            }
        }

        float red = sqrt(pow(GxRed,2) + pow(GyRed,2));
        float green = sqrt(pow(GxGreen,2) + pow(GyGreen,2));
        float blue = sqrt(pow(GxBlue,2) + pow(GyBlue,2));

        if (red > 255)
            red = 255;

        if (green > 255)
            green = 255;

        if (blue > 255)
            blue = 255;

        image[i][j].rgbtRed = round(red);
        image[i][j].rgbtGreen = round(green);
        image[i][j].rgbtBlue = round(blue);
    }
}

return;

}

Answer 1

This happens because the code is attempting to access an array element outside the bounds of the array. Remember that when an array is allocated a size of, say 5, the elements will run from 0 to 4. Height and width are array SIZES, so they each exceed the maximum allowable values by 1.

As for the for loop that the code is using to initialize the array, I don't understand why you're using image[height][width]. I would think that you'd initialize the array by copying the original array (using image[i][j]) or by setting each element to 0 values for each RGBTRIPLE element.

There may be other issues, but this answers the question asked.

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