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9.2 Reading from a file

  1. If needed, start from the project up to chapter 8. This contains the classes as you left them at the end of chapter 8.
  2. Create a new folder in your project named Data.

  3. Create a file Rectangle.csv with the following content and place it in the Data folder: 

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    3,3,0,7,red
3,2,0,4,yellow
5,2,0,2,green
5,2,3,7,purple
5,4,5,7,orange

    Format: length, width, x, y, color

  4. Add the following code to your Main method: 

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    List<Rectangle> rectangles = new List<Rectangle>();
string filePath = "Data/Rectangle.csv";

try
{
    string[] lines = File.ReadAllLines(filePath);
    foreach (string line in lines)
    {
        string[] values = line.Split(',');
        double length = double.Parse(values[0]);
        double width = double.Parse(values[1]);
        double x = double.Parse(values[2]);
        double y = double.Parse(values[3]);
        rectangles.Add(new Rectangle(length, width, new Point(x, y), values[4]));
    }

    foreach (Rectangle rect in rectangles)
    {
        Console.WriteLine(rect);
        Console.WriteLine();
    }
}
catch (FileNotFoundException)
{
    Console.WriteLine("The file was not found.");
}
    • File.ReadAllLines(filePath) can throw a FileNotFoundException. Therefore use a try/catch block.
    • Make sure the file is copied to the output directory: in the .csproj add <Content Include="Data\*.csv" CopyToOutputDirectory="PreserveNewest" /> or set "Copy to Output Directory" to "Copy if newer" in file properties.

  5. Run your program. You will see the information of five rectangles.