Console Input & Output in C#

Use Console.WriteLine, Console.Write, Console.ReadLine, formatted output with string interpolation, and composite formatting.

Console Output Basics

1. Console.WriteLine() (Print with Newline)

`Console.WriteLine()` prints a value followed by a newline. Each call prints on a new line.

2. Console.Write() (Print Without Newline)

`Console.Write()` prints without adding a newline — the next output continues on the same line.

3. Printing Variables (String Interpolation)

Use `$"..."` string interpolation to embed variables directly in a string — the cleanest way to print variables in C#.

4. Console.Error (Writing to stderr)

`Console.Error.WriteLine()` writes to the standard error stream — useful for logging errors separately from normal output.

Formatted Console Output

1. Format Specifiers

Use format specifiers inside `{}` to control number formatting — currency, fixed decimals, percentages, and padding.

2. Print a Simple Table (Aligned Columns)

Use `PadRight()` and `PadLeft()` to align columns and print a formatted table.

3. Composite Formatting (string.Format)

`string.Format()` uses `{0}`, `{1}` placeholders — the older formatting style, still common in logs and legacy code.

Console Input (Reading User Data)

1. Console.ReadLine() (Interactive Input)

`Console.ReadLine()` waits for the user to type a line and press Enter. It always returns a `string?`.

2. Reading a Number

Read a number safely using `int.TryParse()` to avoid exceptions on invalid input.

3. Command-Line Arguments (args[])

Access arguments passed when running the program via `args[]` in the top-level program or `string[] args` in `Main`.

4. Scan Multiple Numbers (Space Separated)

Read a line of space-separated numbers, split it, and parse each value.