CalculatorLibrary.CalculatorCli Class Reference

Parses and runs the calculator's command-line arguments. More...

Static Public Member Functions
static string	Run (string[] args)
	Parses args as <operation> <a> <b> and returns a line of text describing the result.
static string	RunDemo ()
	Runs a small built-in demonstration that exercises every operation once, used when the application is started with no arguments at all (so a first run always shows something, without waiting on keyboard input).

Static Public Attributes
const string	UsageText = "Usage: CalculatorApp <add|subtract|multiply|divide> <a> <b>"
	The usage line shown when the arguments cannot be parsed.

Detailed Description

Parses and runs the calculator's command-line arguments.

The parsing logic lives here, in the library, instead of in CalculatorApp/Program.cs, so it can be unit tested directly (see CalculatorLibrary.Tests/CalculatorCliTests.cs) without spawning the console application as a process. Program.cs only calls Run(string[]) or RunDemo and prints the result — it never reads from the console, so it never blocks when the app is launched from a script, a build pipeline or CI.

When you rename this sample into your own project, replace this class with your own argument-parsing entry point, keeping the same "parsing is a library function, not something the console shell does inline" shape.

Definition at line 20 of file CalculatorCli.cs.

Member Function Documentation

Run()

static string CalculatorLibrary.CalculatorCli.Run ( string[]  args )

static

Parses args as <operation> <a> <b> and returns a line of text describing the result.

Parameters

args	Exactly three arguments: the operation name (add, subtract, multiply or divide, case-insensitive) followed by the two integer operands.

Returns

A human-readable line such as "2 add 2 = 4".

Exceptions

ArgumentException	Thrown when the argument count is wrong, an operand is not a valid 32-bit integer, or the operation name is not recognized. The message always ends with UsageText.
DivideByZeroException	Thrown when dividing by zero.

Definition at line 38 of file CalculatorCli.cs.

                                          {
    if (args.Length != 3) {
      throw new ArgumentException($"Expected 3 arguments (operation, a, b) but got {args.Length}. {UsageText}");
    }
 
    string operation = args[0].Trim().ToLowerInvariant();
 
    if (!int.TryParse(args[1], out int a)) {
      throw new ArgumentException($"'{args[1]}' is not a valid 32-bit integer for <a>. {UsageText}");
    }
 
    if (!int.TryParse(args[2], out int b)) {
      throw new ArgumentException($"'{args[2]}' is not a valid 32-bit integer for <b>. {UsageText}");
    }
 
    var calculator = new Calculator();
 
    int result = operation switch {
      "add" => calculator.Add(a, b),
        "subtract" => calculator.Subtract(a, b),
        "multiply" => calculator.Multiply(a, b),
        "divide" => calculator.Divide(a, b),
        _ => throw new ArgumentException($"Unknown operation '{args[0]}'. {UsageText}"),
    };
 
    return $"{a} {operation} {b} = {result}";
  }

RunDemo()

static string CalculatorLibrary.CalculatorCli.RunDemo ( )

static

Runs a small built-in demonstration that exercises every operation once, used when the application is started with no arguments at all (so a first run always shows something, without waiting on keyboard input).

Returns

The combined demo output, ending with UsageText.

Definition at line 72 of file CalculatorCli.cs.

                                 {
    var calculator = new Calculator();
    var lines = new System.Text.StringBuilder();
    lines.AppendLine("Calculator Application Running (no arguments given, showing the built-in demo)...");
    lines.AppendLine($"2 add 2 = {calculator.Add(2, 2)}");
    lines.AppendLine($"2 multiply 2 = {calculator.Multiply(2, 2)}");
    lines.AppendLine($"2 subtract 2 = {calculator.Subtract(2, 2)}");
    lines.AppendLine($"2 divide 2 = {calculator.Divide(2, 2)}");
    lines.Append(UsageText);
    return lines.ToString();
  }

References CalculatorLibrary.CalculatorCli.UsageText.

Member Data Documentation

UsageText

const string CalculatorLibrary.CalculatorCli.UsageText = "Usage: CalculatorApp <add|subtract|multiply|divide> <a> <b>"

static

The usage line shown when the arguments cannot be parsed.

Definition at line 22 of file CalculatorCli.cs.

Referenced by CalculatorLibrary.CalculatorCli.RunDemo().

---

The documentation for this class was generated from the following file:

• CalculatorLibrary/CalculatorCli.cs