File Handling In C#

File Operations

Create File

In this example, we will learn how to create a text file using the File class and Create() method. At first, we store the file path in a string variable using a verbatim identifier (@). The verbatim string embeds filename, path, and regular expression in our code. We have given the path to creating a text file in the create method. 

using System;
using System.IO;


namespace Studytonight
{
    class Program
    {
        static void Main(string[] args)
        {
            string filepath = @"D:\ninjas.txt";
            File.Create(filepath);
            Console.WriteLine("A text file created successfully.");
        }
    }
}

Output

Delete a File

In the previous example, we learned to create a text file in D drive, and in this example, we first check the presence of the same File that exists at the specified location. If the condition returns true, we will use the Delete method to delete the text file and print the desired outcome on the console. The following example demonstrates how to delete a text file.

using System;
using System.IO;


namespace Studytonight
{
    class Program
    {
        static void Main(string[] args)
        {
            string filepath = @"D:\examplefile.txt";
            if(File.Exists(filepath))
            {
                File.Delete(filepath);
                Console.WriteLine("Existing Text File Deleted.");
            }
         
        }
    }
}

Output

Write in a File

In the earlier example, we have deleted the text file present at a specific location. After the control is out of the if block, we write data to a text file using the WriteAllText method. The WriteAllText method creates a new file regardless of an existing file and writes the detailed data in it. The WriteAllText method overwrites the old File with a new one by writing the data to it if we don't cross-check the condition for a file with the same name on a specified path or not. Lastly, we read the same file data using the ReadAllText method.

using System;
using System.IO;


namespace Studytonight
{
    class Program
    {
        static void Main(string[] args)
        {
            string path = @"D:\examplefile.txt";
            if(File.Exists(path))
            {
                File.Delete(path);
                Console.WriteLine("Existing Text File Deleted.");
            }
            File.WriteAllText(path,"Writing this text file in a file.");
            Console.WriteLine("wrote the text in it after creating a new text file.");
            Console.WriteLine(File.ReadAllText(path));
        }
    }
}

Output

Copy and Move a File

In the previous example, we have given the source and destination to a file. Hence in the try block, we move a text file from D drive to E drive using the Move method. The Copy method, on the other hand, copies the File from one location to another particular location while maintaining the original File at the source location. These are the simple file operations we perform daily.

using System;
using System.IO;


namespace CW
{
    class Program
    {
        static void Main(string[] args)
        {
            string source = @"D:\textfile.txt";
            string destination = @"E:\textfile.txt";
            try
            {
                File.Move(source, destination);
                File.Copy(destination, source);
            }
            catch(FileNotFoundException fnfe)
            {
                Console.WriteLine(fnfe);
            }
        }
    }
}

Output

Let’s move to the FAQ section to clear your minor doubts.

FAQs

1. What is file handling in C#?
   File handling in C# refers to storing data as input or output produced by running C# programs in data files, namely, a text file or a binary file for future reference and analysis.
2. Why do we use file handling in C#?
   File handling in C# helps us create, update, read, and delete the files stored on our local file system through our C# program.
3. How do streams work in C#?
   In C# file operations, usually, streams are used to read and write to files. A stream is an additional layer created between an application and a file. The stream ensures smooth read and writes operations to the File. Streams usually are used when reading data from large files.
4. What are I/O operations in C#?
   The System.IO namespace has various classes used for performing numerous operations with files, such as creating and deleting files, reading from or writing to a file, closing a file, etc.
5. What is the difference between FileStream and MemoryStream in C#?
   As the name suggests, a FileStream reads and writes to a file, whereas a MemoryStream reads and writes to the memory. So it relates to where the stream is stored. 

Recommended Topic -  singleton design pattern in c#

Key Takeaways

In this article, we extensively discussed file handling in C#. We have seen some classes used in file handling operations. We have also learned various examples of creating a file, deleting a file, writing text to a file, etc. To read more about the c#, Visit Here.

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