Build a blackjack calculator at .net: Step Tutorial

Blackjack is a skills and probability game where players can increase their chances by following the basic strategies – the optimal optimal way to play each hand. In this tutorial, we will build a blackjack calculator on .net (c#) which helps players make the best decisions based on their hands and dealer cards.

We will use the basic strategy rules from Sevenjackpots Blackjack Guide To determine the correct movement (press, holding, double, split, or surrender).

Prerequisite

• Visual Studio (2022 or more recent)
• Basic Knowledge of C# Dan .net
• Understanding of blackjack rules

Step 1: Create a new .net console application

1. Open Visual Studio and create a new console application project (.net core)
2. Mention blackjackcalculator and click create

Step 2: Determine Blackjack Strategy Rules
We will encourage the basic strategy into a structured format. The strategy depends on:

• Player’s hand (totally hard, totally soft, pair)
• Dealer Card (2 to Ace)

Total hard (no ace in hand)
For hands like 10-6 (16) or 9-7 (16), the strategy is different from if the player has Ace.

Total Soft (ACE + Other Cards)
Ace can be 1 or 11, so hands like A-5 (soft 16) require different decisions.

Pair (Logic Separation)
If the player has two identical cards (for example, 8-8), the calculator must recommend whether to separate.

We will save this rule in the dictionary for a quick search.

Step 3: Implement Blackjack Logic

1. Determine the strategy table

Add the following dictionary to the program.cs:

using System;
using System.Collections.Generic;

class Program
{
 // Hard totals (player's hand without an Ace)
 private static readonly Dictionary<int, Dictionary<int, string>> HardTotals = new()
 {
    	{ 8, new Dictionary<int, string> { { 2, "H" }, { 3, "H" }, /* ... up to Ace */ } },
    	{ 9, new Dictionary<int, string> { { 2, "H" }, { 3, "D" }, /* ... */ } },
    	// Continue for all hard totals (5-21)
 };

 // Soft totals (player has an Ace)
 private static readonly Dictionary<int, Dictionary<int, string>> SoftTotals = new()
 {
    	{ 13, new Dictionary<int, string> { { 2, "H" }, { 3, "H" }, /* ... */ } },
    	// Continue for all soft totals (A2 to A9)
 };

 // Pairs (when player can split)
 private static readonly Dictionary<int, Dictionary<int, string>> Pairs = new()
 {
    	{ 2, new Dictionary<int, string> { { 2, "P" }, { 3, "P" }, /* ... */ } },
    	// Continue for all pairs (2-10, A)
 };
}

2. Create a method for getting the best steps

Add the method that checks the player’s hand and dealer card to restore optimal steps:

static string GetOptimalMove(int playerTotal, bool isSoft, bool isPair, int dealerUpcard)
{
 if (isPair && Pairs.TryGetValue(playerTotal / 2, out var pairStrategy))
 {
    	if (pairStrategy.TryGetValue(dealerUpcard, out var move))
        	return move;
 }
 else if (isSoft && SoftTotals.TryGetValue(playerTotal, out var softStrategy))
 {
    	if (softStrategy.TryGetValue(dealerUpcard, out var move))
        	return move;
 }
 else if (HardTotals.TryGetValue(playerTotal, out var hardStrategy))
 {
    	if (hardStrategy.TryGetValue(dealerUpcard, out var move))
        	return move;
 }

 return "H"; // Default to Hit if no strategy found
}

3. Conversion Code Move to readings that can be read

Add the helper method to display H (hit), S (holder), D (double), P (split), or R (submission):

static string GetMoveDescription(string moveCode)
{
 return moveCode switch
 {
    	"H" => "Hit",
    	"S" => "Stand",
    	"D" => "Double Down",
    	"P" => "Split",
    	"R" => "Surrender",
    	_ => "Unknown"
 };
}

Step 4: Build the User Interface

Now, let’s make a simple console based UI where users enter their hands and dealer cards.

static void Main()
{
 Console.WriteLine("=== BLACKJACK STRATEGY CALCULATOR ===");
    
 while (true)
 {
    	Console.WriteLine("\nEnter your hand (e.g., '10 6' for 16, 'A 5' for soft 16):");
    	string[] playerInput = Console.ReadLine().Split(' ');
   	 
    	Console.WriteLine("Enter dealer's upcard (2-10, J, Q, K, A):");
    	string dealerInput = Console.ReadLine();

    	// Parse player's hand
    	int playerTotal = 0;
    	bool isSoft = false;
    	bool isPair = playerInput.Length == 2 && playerInput[0] == playerInput[1];

    	foreach (string card in playerInput)
    	{
        	if (card == "A")
        	{
            	playerTotal += 11;
            	isSoft = true;
        	}
        	else if (int.TryParse(card, out int value))
            	playerTotal += value;
        	else if (card == "J" || card == "Q" || card == "K")
            	playerTotal += 10;
    	}

    	// Parse dealer's upcard
    	int dealerUpcard = dealerInput switch
    	{
        	"A" => 11,
        	"J" or "Q" or "K" => 10,
        	_ => int.Parse(dealerInput)
    	};

    	// Get optimal move
    	string move = GetOptimalMove(playerTotal, isSoft, isPair, dealerUpcard);
    	Console.WriteLine($"\nOptimal Move: {GetMoveDescription(move)}");

    	Console.WriteLine("\nCalculate again? (Y/N)");
    	if (Console.ReadLine().ToUpper() != "Y")
        	break;
 }
}

Step 5: Blackjack Calculator Test

Run different programs and screenplay tests:

Example 1: Hard 16 vs. Dealer 10

• Input: 10 6 (Players: 16)
• Dealer: 10
• Expected output: stand (if the surrender is not available) or hit (if submitted is permitted)

Example 2: Soft 18 vs. Dealer 9

• Input: A 7 (Player: Soft 18)
• Dealer: 9
• Expected Output: standing

Example 3: Pair 8S vs. Dealer 5

• Input: 8 8 (Player: Pair 8S)
• Dealer: 5
• Expected Output: Separation

You have just built a blackjack strategy calculator on .net (c#)! This tool will help players make optimal decisions based on the Blackjack strategy which is proven mathematically.