1.4 Basic Input and Output

📌1. Output to Console

The primary way to output in C# is through the Console class.

Print text

Console.WriteLine("Hello, World!"); // Adds a newline
Console.Write("Hello, ");           // Does NOT add a newline
Console.Write("World!");

Print variables

int age = 25;
string name = "Alice";
 
Console.WriteLine("Name: " + name + ", Age: " + age); // Concatenation
Console.WriteLine($"Name: {name}, Age: {age}");      // String interpolation (recommended)
Console.WriteLine("Name: {0}, Age: {1}", name, age); // Composite formatting

✅ Tip: String interpolation ($"...") is the cleanest and easiest to read.

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📌2. Input from Console

The primary way to get user input is Console.ReadLine(). It returns a string, so you may need to convert it for other types.

Console.Write("Enter your name: ");
string name = Console.ReadLine();
 
Console.Write("Enter your age: ");
int age = int.Parse(Console.ReadLine()); // Convert string to int

Safe conversion

Use TryParse to avoid exceptions:

Console.Write("Enter your age: ");
string input = Console.ReadLine();
int age;
 
if (int.TryParse(input, out age))
{
    Console.WriteLine($"You are {age} years old.");
}
else
{
    Console.WriteLine("Invalid number entered!");
}

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📌3. Other Useful Console Methods

• Console.ReadKey() → waits for a key press, can return key info

Console.WriteLine("Press any key to continue...");
Console.ReadKey();

• Console.Clear() → clears the console

• Console.Beep() → plays a beep sound

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📌 4. Example: Simple Input/Output Program

Console.Write("Enter your name: ");
string name = Console.ReadLine();
 
Console.Write("Enter your age: ");
int age = int.Parse(Console.ReadLine());
 
Console.WriteLine($"Hello {name}, you are {age} years old.");

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✅ Summary:

1. Output: Console.WriteLine, Console.Write, string interpolation recommended.

2. Input: Console.ReadLine(), then parse if needed (int.Parse, double.Parse, or TryParse).

3. Extra: Console.ReadKey, Console.Clear for interactive console programs.