【Rust】rustでblockchain

### トランザクション

use std::collections::HashMap;

fn main(){
    let transaction = HashMap::from([
        ("Time", "2024-12-20 13:58"),
        ("sender", "A"),
        ("receiver", "B"),
        ("amount", "1")
    ]);
    for (k, v) in &transaction {
        println!("{} {}", k, v);
    }
}

Hashmapだとkey, valueが全て同じ型になってしまうので、構造体を使用する。

#[derive(Debug)]

struct Transaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
}

fn main(){
    let t1 = Transaction {time: "2024-12-20 13:58".to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};

    println!("{:?}", t1);
}

$ ./main
Transaction { time: “2024-12-20 13:58”, sender: “A”, receiver: “B”, amount: 10 }

複数トランザクションの場合は配列を使用する

fn main(){
    let t1 = Transaction {time: "2024-12-20 13:58".to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};
    let t2 = Transaction {time: "2024-12-21 13:58".to_string(), sender: "B".to_string(), receiver: "C".to_string(), amount: 5};

    let transactions = [t1, t2];
    println!("{:?}", transactions);
}

### Rustで日時を扱う

use chrono::{Utc, Local, DateTime, Date};

fn main(){
    let utc_datetime: DateTime<Utc> = Utc::now();
    let utc_date: Date<Utc> = Utc::today();

    println!("{}", utc_datetime);
    println!("{}", utc_date);
}

2024-12-20 05:46:43.775637762 UTC
2024-12-20UTC

crateを使うには、Cargo.tomlを利用する

[package]
name = "hoge"
version = "0.1.0"
edition = "2021"

[dependencies]
chrono = "0.4.23"

凄い基本的なことを書くだけでも時間がかかりますな。。

use chrono::{Utc, Local, DateTime, Date};
#[derive(Debug)]

struct Transaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
}

fn main(){
    let utc_datetime: DateTime<Utc> = Utc::now();
    let t1 = Transaction {time: utc_datetime.to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};
    let t2 = Transaction {time: utc_datetime.to_string(), sender: "B".to_string(), receiver: "C".to_string(), amount: 5};

    let transactions = [t1, t2];
    println!("{:?}", transactions);
}

[Transaction { time: “2024-12-21 06:09:35.567867379 UTC”, sender: “A”, receiver: “B”, amount: 10 }, Transaction { time: “2024-12-21 06:09:35.567867379 UTC”, sender: “B”, receiver: “C”, amount: 5 }]