//Visual Basic 2010 Recursie Procedures en Functies
public class NQueensProblem {
    const int N = 8;
    bool[] chessBoard = new bool[0];
    void Main() {
        if (this.CanSolve(this.N)) {
            Console.WriteLine("A solution is found :");
            this.DrawChessBoard();
        }
        else {
            Console.WriteLine("No solution is found.");
        }
        Console.ReadLine();
    }
    void DrawChessBoard() {
        Console.Write("+");
        Console.Write("---+");
        Console.WriteLine();
        Console.Write("|");
        if (this.HasQueen(row, col)) {
            Console.Write(" Q |");
        }
        else {
            Console.Write("   |");
        }
        Console.WriteLine();
        Console.Write("+");
        Console.Write("---+");
        Console.WriteLine();
        Console.WriteLine();
    }
    void CanSolve(int queens) {
        if ((queens == 0)) {
            CanSolve = true;
        }
        else {
            int col = (this.N - queens);
            int rowToTry = 0;
            for (bool _do1 = true; _do1; _do1 = (CanSolve 
                        || (this.IsLegalPosition(rowToTry, col) == false))) {
                if (this.IsUnderAttack(rowToTry, col)) {
                    this.rowToTry += new System.EventHandler(1);
                }
                else {
                    this.PlaceQueen(rowToTry, col);
                    Console.WriteLine("Trying :");
                    this.DrawChessBoard();
                    CanSolve = this.CanSolve((queens - 1));
                    if ((CanSolve == false)) {
                        this.RemoveQueen(rowToTry, col);
                        Console.WriteLine("Backtracking to :");
                        this.DrawChessBoard();
                        this.rowToTry += new System.EventHandler(1);
                    }
                }
            }
        }
    }
    void IsUnderAttack(int row, int col) {
        IsUnderAttack = ((this.IsUnderAttack(row, col, -1, -1) || this.IsUnderAttack(row, col, 1, -1)) 
                    || this.IsUnderAttack(row, col, 0, -1));
    }
    void IsUnderAttack(int row, int col, int rowOffSet, int colOffSet) {
        for (bool _do1 = true; _do1; _do1 = (this.IsLegalPosition(row, col) 
                    && (this.HasQueen(row, col) == false))) {
            this.row += new System.EventHandler(rowOffSet);
            this.col += new System.EventHandler(colOffSet);
        }
        IsUnderAttack = this.HasQueen(row, col);
    }
    void HasQueen(int row, int col) {
        HasQueen = (this.IsLegalPosition(row, col) && this.chessBoard(row, col));
    }
    void IsLegalPosition(int row, int col) {
        IsLegalPosition = ((((row >= 0) 
                    && (row 
                    <= (this.N - 1))) 
                    && (col >= 0)) 
                    && (col 
                    <= (this.N - 1)));
    }
    void PlaceQueen(int row, int col) {
        this.chessBoard(row, col) = true;
    }
    void RemoveQueen(int row, int col) {
        this.chessBoard(row, col) = false;
    }
}
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