Simple Voting Contract (clarity)

(define-map votes { candidate: (string-utf8 20) } uint)


;; #[allow(unchecked_data)]
(define-public (vote (candidate (string-utf8 20)))
  (let ((count (default-to u0 (map-get? votes { candidate: candidate }))))
    (begin
      (map-set votes { candidate: candidate } (+ count u1))
      (ok true)
    )
  )
)

(define-public (get-votes (candidate (string-utf8 20)))
  (ok (default-to u0 (map-get? votes { candidate: candidate })))
)

This contract allows users to vote for candidates, with votes stored on-chain. Anyone can cast a vote for a candidate by name, and anyone can check how many votes a candidate has received.

---

🧠 Brief Overview

• Purpose: Tally votes for candidates by name.
• Storage: A map that links each candidate’s name to their vote count.
• Functions:
  • vote: Increases vote count for a candidate.
  • get-votes: Returns the total votes for a candidate.

---

📄 Code Breakdown

🗃️ 1. Define the Votes Map

(define-map votes { candidate: (string-utf8 20) } uint)

• A map called votes tracks vote totals.
• Key: { candidate: string-utf8(20) } — candidate name (max 20 chars).
• Value: uint — the number of votes received.

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✅ 2. Cast a Vote

(define-public (vote (candidate (string-utf8 20)))
  (let ((count (default-to u0 (map-get? votes { candidate: candidate }))))
    (begin
      (map-set votes { candidate: candidate } (+ count u1))
      (ok true)
    )
  )
)

• Public function — anyone can call it to vote.
• Input: candidate — the name of the candidate being voted for.
• Reads current vote count using map-get?.
  • If none yet: defaults to 0 using default-to.
• Adds 1 to the vote count.
• Stores the new count in the map.
• Returns (ok true) as confirmation.

---

📊 3. Get Vote Count

(define-public (get-votes (candidate (string-utf8 20)))
  (ok (default-to u0 (map-get? votes { candidate: candidate })))
)

• Takes the candidate name as input.
• Fetches the number of votes from the map.
• If no votes exist yet, returns 0.
• Always returns result wrapped in ok.

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🧭 Step-by-Step: How It Works

Let’s walk through an example:

🧑 User A votes for “Alice”:

(vote "Alice")

• The contract:
  • Checks if “Alice” has votes → returns 0 (if first vote).
  • Adds 1 → total becomes 1.
  • Stores { candidate: "Alice" } → 1.

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🧑‍🤝‍🧑 User B votes for “Bob”:

(vote "Bob")

• Same logic → { candidate: "Bob" } → 1.

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🧑 User A votes for “Alice” again:

(vote "Alice")

• Reads current count: 1.
• Adds 1 → becomes 2.
• Updates map.

---

📊 Check how many votes “Alice” has:

(get-votes "Alice")

• Returns:

(ok u2)

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📘 Summary Table

Function	Purpose
votes map	Stores each candidate’s vote count
vote	Increments a candidate’s vote count
get-votes	Retrieves vote count for any candidate
default-to	Ensures candidates with no votes return 0

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🧩 Real-World Analogy

Think of a public election box:

• Each candidate’s name is a folder.
• Every time someone votes, a ballot goes into that folder.
• Anyone can check how many ballots (votes) are in any folder.