Group
File Handling in C#
Objective
1. The program will read a Netpbm "P1" format image file.
2. It will ignore any comment lines that start with #.
3. It will read the width and height of the image.
4. It will display the image in the console, using 0 for white pixels and 1 for black pixels.
5. The image will be printed with rows and columns corresponding to the pixel data in the file.
Example usage:
decodePbm j.pbm
The Netpbm format is a family of image file formats designed with simplicity in mind, rather than small size. They can represent color, grayscale, or black and white images using plain text (even though a binary variant exists).
Example C# Exercise
Show C# Code
using System;
using System.IO;
class NetpbmDecoder
{
// Main method where the program starts execution
static void Main(string[] args)
{
// Check if the user provided a filename as a command line argument
if (args.Length != 1)
{
Console.WriteLine("Usage: decodePbm ");
return;
}
// Get the file path from the command line argument
string fileName = args[0];
// Try to read the file
try
{
// Open the file for reading
using (StreamReader reader = new StreamReader(fileName))
{
// Read the magic number (P1) from the file
string magicNumber = reader.ReadLine();
if (magicNumber != "P1")
{
Console.WriteLine("Invalid file format. The file is not a valid P1 Netpbm image.");
return;
}
// Read the comment lines and ignore them if they start with #
string line;
while ((line = reader.ReadLine()) != null && line.StartsWith("#"))
{
// Skip comment lines
}
// Read the width and height of the image
string[] dimensions = line.Split(' ');
int width = int.Parse(dimensions[0]);
int height = int.Parse(dimensions[1]);
// Create a 2D array to store the pixel data
int[,] image = new int[height, width];
// Read the image data
int row = 0;
while ((line = reader.ReadLine()) != null)
{
string[] pixels = line.Split(' ');
for (int col = 0; col < width; col++)
{
image[row, col] = int.Parse(pixels[col]);
}
row++;
}
// Display the image in the console
Console.Clear();
for (int r = 0; r < height; r++)
{
for (int c = 0; c < width; c++)
{
// Display black (1) or white (0) pixels
Console.Write(image[r, c] == 1 ? "1" : "0");
}
Console.WriteLine(); // Move to the next line
}
}
}
catch (Exception ex)
{
Console.WriteLine($"Error reading the file: {ex.Message}");
}
}
}
Output
//Case 1 - Valid image:
//For the command:
decodePbm j.pbm
//Output:
000010
000010
000010
000010
000010
000010
100010
011100
000000
000000
//This would represent the letter "J" in a 6x10 grid, where 1 represents black pixels and 0 represents white pixels.
//Case 2 - Invalid or non-existent file:
//If the file doesn't exist or isn't a valid P1 format, the output might look like:
Usage: decodePbm
Invalid file format. The file is not a valid P1 Netpbm image.