Using SqlDataReader asynchronously prevents blocking the main thread, improving performance in web apps and large queries. Here’s how to do it properly.
Use await with ExecuteReaderAsync()
using (SqlConnection conn = new SqlConnection(connectionString)) { await conn.OpenAsync(); using (SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn)) using (SqlDataReader reader = await cmd.ExecuteReaderAsync()) { while (await reader.ReadAsync()) { Console.WriteLine(reader["Username"]); } } // ✅ Auto-closes reader } // ✅ Auto-closes connection
Why use async?
A couple of reasons:
⚡ Alternative: ConfigureAwait(false) for ASP.NET
Use ConfigureAwait(false) in library code to avoid deadlocks in UI frameworks like ASP.NET.
using (SqlConnection conn = new SqlConnection(connectionString)) { await conn.OpenAsync().ConfigureAwait(false); using (SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn)) using (SqlDataReader reader = await cmd.ExecuteReaderAsync().ConfigureAwait(false)) { while (await reader.ReadAsync().ConfigureAwait(false)) { Console.WriteLine(reader["Username"]); } } }
XML (Extensible Markup Language) is a widely used format for storing and transporting data.
In C#, you can create XML files efficiently using the XmlWriter and XDocument classes. This guide covers both methods with practical examples.
XmlWriter
XDocument
XmlWriter provides a fast and memory-efficient way to generate XML files by writing elements sequentially.
using System; using System.Xml; class Program { static void Main() { using (XmlWriter writer = XmlWriter.Create("person.xml")) { writer.WriteStartDocument(); writer.WriteStartElement("Person"); writer.WriteElementString("FirstName", "John"); writer.WriteElementString("LastName", "Doe"); writer.WriteElementString("Age", "30"); writer.WriteEndElement(); writer.WriteEndDocument(); } Console.WriteLine("XML file created successfully."); } }
Output (person.xml):
person.xml
<?xml version="1.0" encoding="utf-8"?> <Person> <FirstName>John</FirstName> <LastName>Doe</LastName> <Age>30</Age> </Person>
The XDocument class from LINQ to XML provides a more readable and flexible way to create XML files.
using System; using System.Xml.Linq; class Program { static void Main() { XDocument doc = new XDocument( new XElement("Person", new XElement("FirstName", "John"), new XElement("LastName", "Doe"), new XElement("Age", "30") ) ); doc.Save("person.xml"); Console.WriteLine("XML file created successfully."); } }
This approach is ideal for working with complex XML structures and integrating LINQ queries.
Writing XML files in C# is straightforward with XmlWriter and XDocument. Choose the method that best suits your needs for performance, readability, and maintainability.
Reading a file line by line is useful when handling large files without loading everything into memory at once.
✅ Best Practice: Use File.ReadLines() which is more memory efficient.
Example
foreach (string line in File.ReadLines("file.txt")) { Console.WriteLine(line); }
Why use ReadLines()?
Reads one line at a time, reducing overall memory usage. Ideal for large files (e.g., logs, CSVs).
Alternative: Use StreamReader (More Control)
For scenarios where you need custom processing while reading the contents of the file:
using (StreamReader reader = new StreamReader("file.txt")) { string? line; while ((line = reader.ReadLine()) != null) { Console.WriteLine(line); } }
Why use StreamReader?
Lets you handle exceptions, encoding, and buffering. Supports custom processing (e.g., search for a keyword while reading).
When to Use ReadAllLines()? If you need all lines at once, use:
string[] lines = File.ReadAllLines("file.txt");
Caution: Loads the entire file into memory—avoid for large files!
Storing passwords as plain text is dangerous. Instead, you should hash them using a strong, slow hashing algorithm like BCrypt, which includes built-in salting and resistance to brute-force attacks.
Step 1: Install BCrypt NuGet Package
Before using BCrypt, install the BCrypt.Net-Next package:
dotnet add package BCrypt.Net-Next
or via NuGet Package Manager:
Install-Package BCrypt.Net-Next
Step 2: Hash a Password
Use BCrypt.HashPassword() to securely hash a password before storing it:
using BCrypt.Net; string password = "mySecurePassword123"; string hashedPassword = BCrypt.HashPassword(password); Console.WriteLine(hashedPassword); // Output: $2a$12$...
Step 3: Verify a Password
To check a user's login attempt, use BCrypt.Verify():
bool isMatch = BCrypt.Verify("mySecurePassword123", hashedPassword); Console.WriteLine(isMatch); // Output: True
Ensuring proper hashing should be at the top of your list when it comes to building authentication systems.
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