How to print matrix?

Question

public override string ToString() {
    string matrixView = "";

    for (int r=0; r<=this.rows; r++) {
        for (int c=0; c<=this.columns; c++) {
                
        }
    }

    return matrixView;
}

Note:
##################################
this.rows = row number
this.columns = column number
this.matrix= 2-dimensional array used as data store
##################################

In this code, I aim to make seem for example 4x4 matrix like:

[0 0 0 0]
[0 0 0 0]
[0 0 0 0]
[0 0 0 0]

Each newline must be started with "[". Values(this.columns times) and spaces(this.columns-1 times) must be printed. Finally, the line must be ended with "]\n" And these operations above must be done this.rowstimes.

I think in this way. But nested loops always make me confuse. So, I tried several times but I couldn't be successful at it. And String.Concat threw NullReferenceExceptionwhen I tried to concaten matrixView with "[", "]\n" and this.matrix[r, c].ToString().

Answer 1

I think you are looking for something like this:

public override string ToString() {
    // When building string, better use StringBuilder instead of String
    StringBuilder matrixView = new StringBuilder();

    // Note r < matrix.GetLength(0), matrix is zero based [0..this.rows - 1]
    // When printing array, let's query this array - GetLength(0)
    for (int r = 0; r < matrix.GetLength(0); r++) {
        // Starting new row we should add row delimiter 
        if (r > 0)
            matrixView.AppendLine();

        // New line starts from [
        matrixView.Append("["); 

        // Note r < matrix.GetLength(1), matrix is zero based [0..this.rows - 1]
        for (int c = 0; c < matrix.GetLength(1); c++) {
            // Starting new column we should add column delimiter 
            if (c > 0)
                matrixView.Append(' ');

            matrixView.Append(matrix[r, c]);       
        }

        // New line ends with [
        matrixView.Append("]");
    }

    return matrixView.ToString();
}