Strings

Lesson 6
Author : Afrixi
Last Updated : February, 2023
C# - Programming Language
This course covers the basics of programming in C#.

In C#, a string is a sequence of characters that represents text. Strings are used extensively in C# programs for tasks such as displaying text on the screen, storing user input, and manipulating text data.

Here are some important things to know about strings in C#:

Strings are reference types: This means that when you declare a string variable, you’re actually creating a reference to a string object in memory. This is in contrast to value types like integers, which are stored directly in memory.

String literals: You can declare a string literal by enclosing the text in double quotes. For example: string str = "Hello, world!";

Concatenation: You can concatenate (or join) strings using the + operator. For example:

string firstName = "John"; 
string lastName = "Doe"; 
string fullName = firstName + " " + lastName;

String interpolation: You can embed values within a string using string interpolation. This involves enclosing the value in curly braces {} within a string literal, and prefixing the string with a $ character. For example:

int age = 30; 
string message = $"My age is {age}.";

Length: You can determine the length of a string using the Length property. For example:

string str = "Hello, world!"; 
int length = str.Length;

Indexing: You can access individual characters in a string using indexing. For example: string str = "Hello, world!"; char firstChar = str[0];

String methods: There are many built-in methods for working with strings in C#, such as ToUpper(), ToLower(), Substring(), IndexOf(), Replace(), and Split(). These methods can be used to perform tasks like converting a string to uppercase, extracting a substring, finding the index of a character, replacing text within a string, and splitting a string into substrings.

Here’s an example of how to use some of these string features in C#:

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            // Declare a string variable
            string str = "Hello, world!";

            // Concatenate strings
            string firstName = "John";
            string lastName = "Doe";
            string fullName = firstName + " " + lastName;

            // String interpolation
            int age = 30;
            string message = $"My name is {fullName} and I am {age} years old.";

            // Length
            int length = str.Length;

            // Indexing
            char firstChar = str[0];

            // String methods
            string upperCase = str.ToUpper();
            string lowerCase = str.ToLower();
            string substring = str.Substring(7, 5);
            int index = str.IndexOf("world");
            string replaced = str.Replace("world", "C#");
            string[] parts = str.Split(",");

            // Output values to console
            Console.WriteLine(str);
            Console.WriteLine(fullName);
            Console.WriteLine(message);
            Console.WriteLine(length);
            Console.WriteLine(firstChar);
            Console.WriteLine(upperCase);
            Console.WriteLine(lowerCase);
            Console.WriteLine(substring);
            Console.WriteLine(index);
            Console.WriteLine(replaced);
            Console.WriteLine(parts[0]);
            Console.WriteLine(parts[1]);

            Console.ReadKey();
        }
    }
}

In this example, we’re declaring a string variable str and initializing it with the value "Hello, world!". We’re then demonstrating various string features, such as concatenation, string interpolation, length, indexing, and string methods. We’re outputting the values