Welcome to the first lesson of our course on "Parsing Table Data in C#". In this lesson, we will delve into reading and processing table-like data from a text file using C#. This skill is essential for data analysis, report generation, and numerous other applications that require structured data handling in software development. By the end of this lesson, you'll understand how to parse a 2D table from a file and represent it using C# arrays.

Imagine you have a file named students_marks.txt with the following content:

Plain text
Copy to clipboard
15 4 5 5
23 2 3 4
34 4 3 5
43 4 5 4

This file represents a 2D table where each row corresponds to a student's marks across four subjects. In C#, you can use a 2D array or a list of integer arrays to store this data.

To begin, we can use File.ReadAllLines to read all lines from the file. This method retrieves each line as an array of strings, one string per line.

C#
Copy to clipboard
1// Read the entire file and store the lines into an array
2string[] lines = File.ReadAllLines("students_marks.txt"); 

Here, File.ReadAllLines("students_marks.txt") opens and reads the file content into a string array, with each element representing a line from the file.

Now that we have the lines from the file stored in a string[], we need to convert these lines into a format that's easier to work with, like a 2D array of integers. We'll do this in two steps:

1. Split each line into numbers: Each line is a single string where numbers are separated by spaces. First, we'll split each line string into individual number strings using Split(' '), which separates the string wherever there's a space.

2. Convert the number strings to integers: After splitting the string into parts, we'll convert each part into an integer using int.Parse. This converts the string representations of numbers into actual integer data types.

Here’s how you can transform each line to an array of integers and then combine all these arrays into a 2D array:

C#
Copy to clipboard
1// Parse each line into an integer array and gather all rows into a 2D array
2var data = lines
3    .Select(line => line
4        .Split(' ')          // Split the line by spaces into strings
5        .Select(int.Parse)   // Convert strings to integers
6        .ToArray())          // Form an array of integers from the line
7    .ToArray();              // Combine all line arrays into a 2D array

By leveraging LINQ (Language Integrated Query), we efficiently split each line into parts, convert those parts into integers, and assemble the results into a 2D array.

Here's how the students_marks.txt content is represented in a 2D array:

Each row in the table corresponds to a line from the file, and each column corresponds to a number in that line. This tabular representation shows how the data is structured in memory after parsing.

Now, let's make sure we've parsed the data correctly by printing the 2D array.

C#
Copy to clipboard
1Console.WriteLine("Parsed Table Data:");
2foreach (var row in data) // Iterate over each row in the 2D array
3{
4    Console.WriteLine(string.Join(" ", row)); // Join each element of the row into a single string with spaces and print it
5}

This approach leverages string.Join to concatenate elements of each row, separated by spaces, and prints the joined string.

Expected Output:

Plain text
Copy to clipboard
15 4 5 5
23 2 3 4
34 4 3 5
43 4 5 4

In this lesson, we explored how to parse table data from a file in C# using System.IO and LINQ. We employed File.ReadAllLines to handle file input and parsed data into a 2D array for ease of manipulation. Understanding how to handle file input and represent data in structured forms like arrays is crucial in many real-world programming scenarios.

You're now ready to proceed to the practice exercises. These exercises will reinforce your new knowledge by encouraging you to apply similar techniques to other file formats and sizes, honing your skills in structured data manipulation in C#. Enjoy the hands-on experience, and see you in the next lesson!