Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Decimal、正しく使ってる? / Are you using Decimal correctly?
Search
Elvis Shi
December 15, 2021
Programming
4
590
Decimal、正しく使ってる? / Are you using Decimal correctly?
Elvis Shi
December 15, 2021
Tweet
Share
More Decks by Elvis Shi
See All by Elvis Shi
SwiftUIで使いやすいToastの作り方 / How to build a Toast system which is easy to use in SwiftUI
lovee
3
200
SwiftUIで二重スクロール作ってみた / When I tried to make a dual-scroll-ish view in SwiftUI
lovee
1
190
Observation のあれこれ / A brief introduction about Observation
lovee
3
310
ChatGPT 時代の勉強 / Learning under ChatGPT era
lovee
24
7.4k
属人化しない為の勉強会作り / To make tech meetups with less personal dependencies
lovee
0
220
偏見と妄想で語るスクリプト言語としての Swift / Swift as a Scripting Language
lovee
2
660
danger-swift-kantoku
lovee
1
420
A story about me trying to make a router that manages when, how and which view to transit in a SwiftUI app
lovee
1
340
M1チップの脆弱性M1raclesを読み解く / About the vulnerability on M1 chip called M1racles
lovee
2
1.6k
Other Decks in Programming
See All in Programming
Jetpack Composeとデザインシステム
rmakiyama
0
220
仕様と実装で学ぶOpenTelemetry
drumato
2
470
WebGLで始める コンピュータグラフィックス入門
heller77
0
370
TypeScriptのパフォーマンス改善
yajihum
13
5k
Namespace, What and Why
tagomoris
3
640
RaaP
ksss
0
150
RubyGems on ruby.wasm
kateinoigakukun
0
110
株式会社ゼネテック
genetec
0
120
TSKaigi 2024 - 新サービス Progate Path の演習で TypeScript を採用して見えた教材観点からの利点と課題
makotoshimazu
1
220
教えて!スクラムコーチ品質とスピードのバランスはどうすりゃいいの?
pinboro
0
100
Embedding it into Ruby code
soutaro
0
250
CREってこういうこと? 体験入社 - 提案資料 - / what-is-cre-trial-employment
shinden
1
620
Featured
See All Featured
How to Ace a Technical Interview
jacobian
273
22k
Pencils Down: Stop Designing & Start Developing
hursman
117
11k
Designing with Data
zakiwarfel
96
4.8k
Debugging Ruby Performance
tmm1
70
11k
How to train your dragon (web standard)
notwaldorf
75
5.2k
ReactJS: Keep Simple. Everything can be a component!
pedronauck
660
120k
A Tale of Four Properties
chriscoyier
153
22k
What's in a price? How to price your products and services
michaelherold
238
11k
10 Git Anti Patterns You Should be Aware of
lemiorhan
649
58k
Mobile First: as difficult as doing things right
swwweet
217
8.6k
How GitHub (no longer) Works
holman
305
140k
The World Runs on Bad Software
bkeepers
PRO
61
6.7k
Transcript
%FDJNBMɺਖ਼ͬͯ͘͠Δʁ forJ1IPOF%FW4BQQPSPGFBU)","5"TXJGU
} var employedBy = "YUMEMI Inc." var job = "iOS
Tech Lead" var favoriteLanguage = "Swift" var twitter = "@lovee" var qiita = "lovee" var github = "el-hoshino" var additionalInfo = """ M1 Max MacBook Proࠓಧ͍ͨʂ """ final class Me: Developable, Talkable {
ʲใʳΏΊΈɺ҉߸௨՟Λൃߦʂ ˞ӕͰ͢ɻ
ͱ͍͏Θ͚Ͱ ΏΊΈͷڅ༩:VNF$PJOͰࢧڅʹ ˞ӕͰ͢ɻ
// ࠓ݄ͷڅ༩ var myYumeCoin = 0.2 // ࠓ݄ͷϘʔφε myYumeCoin +=
0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // ߴ֬ೝ print(myYumeCoin) // 0.20000000000000004 ??????
ͳͥ͜Μͳ͜ͱ͕ى͜Δͷ͔ w 4XJGUͰখΛѻ͏ͱ͖ɺσϑΥϧτͰDouble͕ ΘΕΔ w Doubleʮഒਫ਼ුಈখʯͳͷͰɺਫ਼ͷ Ͱͦͦਖ਼֬ʹදͤͳ͍ࣈ͕ͨ͘͞Μ͋Δ w େͷ߹ͦͷؙΊΒΕͨࣈͰʹͳΒͳ͍ ͕ɺۚ༥ܥͳͲͷ߹ਖ਼֬ʹѻ͏ඞཁ͕͋Δ
Decimal
Decimalܕ w ුಈখΛेਐϕʔεͰѻ͏ͨΊͷܕ w ༗ޮܻ͕ܻ w ༗ޮܻൣғͰ͋Εेਐදهͷޡ͕ࠩͳ͍
// ࠓ݄ͷڅ༩ var myYumeCoin = 0.2 // ࠓ݄ͷϘʔφε myYumeCoin +=
0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // ߴ֬ೝ print(myYumeCoin) // 0.20000000000000004 ??????
import Foundation // ࠓ݄ͷڅ༩ var myYumeCoin: Decimal = 0.2 //
ࠓ݄ͷϘʔφε myYumeCoin += 0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // ߴ֬ೝ print(myYumeCoin) // 0.2 🎉 'PVOEBUJPO͕ඞཁ ܕΛ໌ࣔతʹ%FDJNBMʹࢦఆ
DecimalɺŜƃŤƄƃŬžŜŘŢŦ
DecimalɺŜƃŤƄƃŬžŜŘŢŦ ͱɺࢥͬͨʁ
import Foundation // ࠓ݄ͷڅ༩ var myYumeCoin: Decimal = 0.2 //
ࠓ݄ͷϘʔφε myYumeCoin += 0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // ߴ֬ೝ print(myYumeCoin) // 0.2 🎉
import Foundation // ࠓ݄ͷڅ༩ var myYumeCoin: Decimal = 0.2 //
ࠓ݄ͷϘʔφε myYumeCoin += 0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // Decimal Λͬͯਖ਼֬ͳڅ༩ܭࢉ͕Ͱ͖͔ͨΒ͍͑Ϙʔφεʂ myYumeCoin += 123.456 // ߴ֬ೝ print(myYumeCoin) // 123.65599999999997952 !!!?????
DecimalɺūŬŹƂŜŽūŘ
DecimalͷϦςϥϧೖ w খϦςϥϧͰDecimalΛೖͰ͖Δͷɺ ExpressibleByFloatLiteralΛར༻ͨ݁͠Ռ w ࣮init(floatLiteral value: Double) w DecimalΛ࡞ΔલʹͦͦઌʹҰճDoubleΛ
࡞ͬͯͦͷ݁ՌΛೖ͍ͯ͠Δ͚ͩʂ
খϦςϥϧͰ DecimalΛೖ͠ͳ͍Ͱʂ
%FDJNBMΛखܰʢʁʣʹѻ͏ͨΊͷ ΠχγϟϥΠβʔ • init(_ value: String, format: Decimal.FormatStyle, lenient:
Bool = true) throws // iOS 15+ • init?(string: String, locale: Locale? = nil) // iOS 7+ • // etc…
import Foundation // ࠓ݄ͷڅ༩ var myYumeCoin: Decimal = 0.2 //
ࠓ݄ͷϘʔφε myYumeCoin += 0.1 // ϘʔφεΛͬͯങ͍ʂ myYumeCoin -= 0.1 // Decimal Λͬͯਖ਼֬ͳڅ༩ܭࢉ͕Ͱ͖͔ͨΒ͍͑Ϙʔφεʂ myYumeCoin += 123.456 // ߴ֬ೝ print(myYumeCoin) // 123.65599999999997952 !!!?????
import Foundation // … // Decimal Λͬͯਖ਼֬ͳڅ༩ܭࢉ͕Ͱ͖͔ͨΒ͍͑Ϙʔφεʂ //myYumeCoin += 123.456
// ࠓͦ͜ʂ myYumeCoin += try! .init("123.456", format: .number) // ߴ֬ೝ print(myYumeCoin) // 123.656 🎉
DecimalɺͪΐͬͱͰ͖͔ͨͳ
ʲࢀߟʳ
IUUQTGPSVNTTXJGUPSHUIPXUPJOJUJBMJ[FEFDJNBM
IUUQTJEFBMSFBMJUZDPNQSPHSBNJOHTXJGUEFDJNBMTUSJOH
ʲએʳ
IUUQTZVNFNJDPOOQBTTDPNFWFOU
IUUQTXXXZVNFNJDPKQDBUFHPSZSFDSVJU