Counter

listings/ch00-introduction/counter/.gitignore

@@ -0,0 +1 @@
+target

listings/ch00-introduction/counter/Scarb.toml

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+[package]
+name = "counter"
+version = "0.1.0"
+
+[dependencies]
+starknet = "1.1.0"
+
+[[target.starknet-contract]]

listings/ch00-introduction/counter/src/counter.cairo

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+#[contract]
+mod SimpleCounter {
+ struct Storage {
+ // Counter variable
+ _counter: u256,
+ }
+
+ #[constructor]
+ fn constructor() {}
+
+ #[view]
+ fn get_current_count() -> u256 {
+ return _counter::read();
+ }
+
+ #[external]
+ fn increment() {
+ // Store counter value + 1
+ let counter: u256 = _counter::read() + 1;
+ _counter::write(counter);
+ }
+
+ #[external]
+ fn decrement() {
+ // Store counter value - 1
+ let counter: u256 = _counter::read() - 1;
+ _counter::write(counter);
+ }
+}

listings/ch00-introduction/counter/src/lib.cairo

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+mod counter;

src/SUMMARY.md

@@ -13,7 +13,8 @@ Summary
  - [Function Attributes](./ch00-08-function_attributes.md)
  - [If statements](./ch00-09-if_statements.md)
  - [Events](./ch00-10-events.md)
+ - [Counter](./ch00-11-counter.md)
 
 - [Applications](./ch01-00-applications.md)
  - [Upgradeable Contract](./ch01-01-upgradeable_contract.md)
- - [Defi Vault](./ch01-02-simple_vault.md)
+ - [Defi Vault](./ch01-02-simple_vault.md)

src/ch00-11-counter.md

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+# Simple Counter
+
+This is a smiple counter contract.
+
+Here's how it works:
+
+- The contract has a state variable called 'counter' that is initialized to 0.
+
+- When a user calls 'increment', the contract increments the counter by 1.
+
+- When a user calls 'decrement', the contract decrements the counter by 1.
+
+```rust
+{{#include ../listings/ch00-introduction/counter/src/counter.cairo}}
+```