C# Professional - Processing Text

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Next: Regular Expressions - Basics

Strings and Encoding

Basics

String is a type from the System namespace that is used for most of text related operations.

The String type has some specificities compared to other types:

It is a reference type
It is immutable, meaning that you cannot change the value of a String
It behaves like a value type

Encodings

Encoding is used to specify:

How text is stored in memory
How text is displayed on screen

The Encoding type offers multiple common encodings:

Default (avoid using this one)
ASCII
Unicode
UTF7
UTF8
UTF32

Text in String instances is stored using Unicode 16. You can include specific Unicode characters in a String using the syntax \u03a0 (here it is the pi character for exemple).

// { 
using System;
using System.Text;
class Example 
{
    static void Main() 
    {
// }
        string unicodeString = "Maths use \u03a0 (Pi) for calculations";
        // You can convert a string into a byte array
        byte[] asciiBytes = Encoding.ASCII.GetBytes(unicodeString);
        // You can convert a byte array into a char array
        char[] asciiChars = Encoding.ASCII.GetChars(asciiBytes);
        string asciiString = new string(asciiChars);
        // The resulting string is different due to the unsupported character for ASCII encoding
        Console.WriteLine($"Unicode string: {unicodeString}");
        Console.WriteLine($"ASCII string: {asciiString}");
// {   
    }   
}
// }

Building `Strings`

As we saw before, String is immutable, which implies that every time you want to modify a String, a new instance will be created. If you have an important number of modifications to do, this can cause a big memory consumption and pressure on the memory.

In order to avoid this scenario, the .Net Framework propose the StringBuilderclass, which is designed for handling such scenarios.

// {
using System;
using System.Text;
using System.Collections.Generic;
class Car 
{
    public string Model { get; set; }
    public string Brand { get; set; }
    public int Year { get; set; }
}
class Example 
{
    private static List<Car> GetListOfCars()
    {
        return new List<Car> {
            new Car { Brand = "Audi", Model = "A6", Year = 2001 },
            new Car { Brand = "Citroen", Model = "C4 Picasso", Year = 2015 },
            new Car { Brand = "Peugeot", Model = "5008", Year = 2011 },
        };
    }
    static void Main() 
    {
// }
        var cars = GetListOfCars();
        // You can initialize the StringBuilder with a default string
        var builder = new StringBuilder("brand, model, year");
        builder.AppendLine();
        // StringBuilder will modify the content without creating new String instance
        foreach(var car in cars)
        {
            builder.AppendLine($"{car.Brand}, {car.Model}, {car.Year}");
        }
        // You can replace text already in StringBuilder buffer
        builder.Replace("5008", "3008");
        Console.WriteLine(builder.ToString());
// {
    }
}
// }

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1/4 Working with Strings and Encoding

Strings and Encoding

Basics

Encodings

Building Strings

Regular Expressions Basics

C# Professional - Basics & OOP - Exercises

C# Professional - Collections - Exercises

C# Tutorial - Part 1: Intro

Building `Strings`