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Daily Challenge #49 - Dollars and Cents

thepracticaldev profile image dev.to staff ・1 min read

Daily Challenge (273 Part Series)

1) Daily Challenge #1 - String Peeler 2) Daily Challenge #2 - String Diamond 3 ... 271 3) Daily Challenge #3 - Vowel Counter 4) Daily Challenge #4 - Checkbook Balancing 5) Daily Challenge #5 - Ten Minute Walk 6) Daily Challenge #6 - Grandma and her friends 7) Daily Challenge #7 - Factorial Decomposition 8) Daily Challenge #8 - Scrabble Word Calculator 9) Daily Challenge #9 - What's Your Number? 10) Daily Challenge #10 - Calculator 11) Daily Challenge #11 - Cubic Numbers 12) Daily Challenge #12 - Next Larger Number 13) Daily Challenge #13 - Twice Linear 14) Daily Challenge #14 - Square into Squares 15) Daily Challenge #15 - Stop gninnipS My sdroW! 16) Daily Challenge #16 - Number of People on the Bus 17) Daily Challenge #17 - Double Trouble 18) Daily Challenge #18 - Triple Trouble 19) Daily Challenge #19 - Turn numbers into words 20) Daily Challenge Post #20 - Number Check 21) Daily Challenge #21 - Human Readable Time 22) Daily Challenge #22 - Simple Pig Latin 23) Daily Challenge #23 - Morse Code Decoder 24) Daily Challenge #24 - Shortest Step 25) Daily Challenge #25 - Double Cola 26) Daily Challenge #26 - Ranking Position 27) Daily Challenge #27 - Unlucky Days 28) Daily Challenge #28 - Kill the Monster! 29) Daily Challenge #29 - Xs and Os 30) Daily Challenge #30 - What is the price? 31) Daily Challenge #31 - Count IPv4 Addresses 32) Daily Challenge #32 - Hide Phone Numbers 33) Daily Challenge #33 - Did you mean...? 34) Daily Challenge #34 - WeIrD StRiNg CaSe 35) Daily Challenge #35 - Find the Outlier 36) Daily Challenge #36 - Let's go for a run! 37) Daily Challenge #37 - Name Swap 38) Daily Challenge #38 - Middle Name 39) Daily Challenge #39 - Virus 40) Daily Challenge #40 - Counting Sheep 41) Daily Challenge #41 - Greed is Good 42) Daily Challenge #42 - Caesar Cipher 43) Daily Challenge #43 - Boardgame Fight Resolver 44) Daily Challenge #44 - Mexican Wave 45) Daily Challenge #45 - Change Machine 46) Daily Challenge #46 - ??? 47) Daily Challenge #47 - Alphabets 48) Daily Challenge #48 - Facebook Likes 49) Daily Challenge #49 - Dollars and Cents 50) Daily Challenge #50 - Number Neighbor 51) Daily Challenge #51 - Valid Curly Braces 52) Daily Challenge #52 - Building a Pyramid 53) Daily Challenge #53 - Faro Shuffle 54) Daily Challenge #54 - What century is it? 55) Daily Challenge #55 - Building a Pile of Cubes 56) Daily Challenge #56 - Coffee Shop 57) Daily Challenge #57 - BMI Calculator 58) Daily Challenge #58 - Smelting Iron Ingots 59) Daily Challenge #59 - Snail Sort 60) Daily Challenge #60 - Find the Missing Letter 61) Daily Challenge #61 - Evolution Rate 62) Daily Challenge #62 - Josephus Survivor 63) Daily Challenge #63- Two Sum 64) Daily Challenge #64- Drying Potatoes 65) Daily Challenge #65- A Disguised Sequence 66) Daily Challenge #66- Friend List 67) Daily Challenge #67- Phone Directory 68) Daily Challenge #68 - Grade Book 69) Daily Challenge #69 - Going to the Cinema 70) Daily Challenge #70 - Pole Vault Competition Results 71) Daily Challenge #71 - See you next Happy Year 72) Daily Challenge #72 - Matrix Shift 73) Daily Challenge #73 - ATM Heist 74) Daily Challenge #74 - Free Pizza 75) Daily Challenge #75 - Set Alarm 76) Daily Challenge #76 - Bingo! (or not...) 77) Daily Challenge #77 - Bird Mountain 78) Daily Challenge #78 - Number of Proper Fractions with Denominator d 79) Daily Challenge #79 - Connect Four 80) Daily Challenge #80 - Longest Vowel Change 81) Daily Challenge #81 - Even or Odd 82) Daily Challenge #82 - English Beggars 83) Daily Challenge #83 - Deodorant Evaporator 84) Daily Challenge #84 - Third Angle of a Triangle 85) Daily Challenge #85 - Unwanted Dollars 86) Daily Challenge #86 - Wouldn't, not Would. 87) Daily Challenge #87 - Pony Express 88) Daily Challenge #88 - Recursive Ninjas 89) Daily Challenge #89 - Extract domain name from URL 90) Daily Challenge #90 - One Step at a Time 91) Daily Challenge #91 - Bananas 92) Daily Challenge #92 - Boggle Board 93) Daily Challenge #93 - Range Extraction 94) Daily Challenge #94 - Last Digit 95) Daily Challenge #95 - CamelCase Method 96) Daily Challenge #96 - Easter Egg Crush Test 97) Daily Challenge #97 - Greed is Good 98) Daily Challenge #98 - Make a Spiral 99) Daily Challenge #99 - Balance the Scales 100) Daily Challenge #100 - Round Up 101) Daily Challenge #101 - Parentheses Generator 102) Daily Challenge #102 - Pentabonacci 103) Daily Challenge #103 - Simple Symbols 104) Daily Challenge #104 - Matrixify 105) Daily Challenge #105 - High-Sum Matrix Drop 106) Daily Challenge #106 - Average Fuel Consumption 107) Daily Challenge #107 - Escape the Mines 108) Daily Challenge #108 - Find the Counterfeit Coin 109) Daily Challenge #109 - Decorate with Wallpaper 110) Daily Challenge #110 - Love VS. Friendship 111) Daily Challenge #111 - 99 Bottles of Beer 112) Daily Challenge #112 - Functions of Integers on the Cartesian Plane 113) Daily Challenge #113 - Iterative Rotation Cipher 114) Daily Challenge #114 - Speed Control 115) Daily Challenge #115 - Look and Say Sequence 116) Daily Challenge #116 - Shortest Knight Path 117) Daily Challenge #117 - MinMinMax 118) Daily Challenge #118 - Reversing a Process 119) Daily Challenge #119 - Adding Big Numbers 120) Daily Challenge #120 - Growth of a Population 121) Daily Challenge #121 - Who has the most money? 122) Daily Challenge #122 - Clockwise Spirals 123) Daily Challenge #123 - Curry me Softly 124) Daily Challenge #124 - Middle Me 125) Daily Challenge #125 - 23 Matches or More 126) Daily Challenge #126 - The Supermarket Line 127) Daily Challenge #127 - Playing with Passphrases 128) Daily Challenge #128 - Blackjack Scorer 129) Daily Challenge #129 - Clay Pigeon Shooting 130) Daily Challenge #130 - GCD Sum 131) Daily Challenge #131 - Remove Anchor from URL 132) Daily Challenge #132 - Is my friend cheating? 133) Daily Challenge #133 - Suitcase Packing 134) Daily Challenge #134 - Rice and Chessboard Problem 135) Daily Challenge #135 - The Wide Mouthed Frog! 136) Daily Challenge #136 - The Deaf Rats of Hamelin 137) Daily Challenge #137 - Help the Bookseller 138) Daily Challenge #138 - Do I get a Bonus? 139) Daily Challenge #138 - Keep Up the Hoop 140) Daily Challenge #140 - I love you, a little, a lot, passionately ... not at all 141) Daily Challenge #141 - Two Sum 142) Daily Challenge #142 - Parts of a Whole 143) Daily Challenge #143 - Big Arithmetic 144) Daily Challenge #144 - Box Office Clerk 145) Daily Challenge #145 - SET Card Game 146) Daily Challenge #146 - The Dollar Game 147) Daily Challenge #147 - NIM 148) Daily Challenge #148 - Disemvowel Trolls 149) Daily Challenge #149 - Fun with Lamps 150) Daily Challenge #150 - Boggle Guess Validator 151) Daily Challenge #151 - Reverse Parentheses 152) Daily Challenge #152 - Strongest Number in an Interval 153) Daily Challenge #153 - Horse Race Gamble 154) Daily Challenge #154 - Stable Arrangement 155) Daily Challenge #155 - Royal Arranged Marriages 156) Daily Challenge #162 - Taxi Dispatching 157) Daily Challenge #163 - Significant Figures 158) Daily Challenge #164 - Jump 159) Daily Challenge #165 - Password Lost in a Grid 160) Daily Challenge #166 - Cat and Mouse 161) Daily Challenge #167 - Return String As Sorted Blocks 162) Daily Challenge #168 - [Code golf] f (f (f b)) = f b 163) Daily Challenge #169 - Christmas Tree 164) Daily Challenge #170 - Pokemon Damage Calculator 165) Daily Challenge #171 - Ordering Beers in Poland 166) Daily Challenge #172 - Find All in an Array 167) Daily Challenge #173 - Pandemia 168) Daily Challenge #174 - Soccer League Table 169) Daily Challenge #175 - Complementary DNA 170) Daily Challenge #176 - Loopover 171) Daily Challenge #177 - Supersize Me 172) Daily Challenge #178 - Create Phone Numbers 173) Daily Challenge #179 - Hide Phone Numbers 174) Daily Challenge #180 - SMS Shortener 175) Daily Challenge #181 - Is King in Check? 176) Daily Challenge #182 - Arrh, grabscrab! 177) Daily Challenge #183 - Automorphic Numbers 178) Daily Challenge #184 - Form the Minimum 179) Daily Challenge #185 - House Numbers Sum 180) Daily Challenge #186 - Jumping Frog 181) Daily Challenge #187 - Most Sales 182) Daily Challenge #188 - Break camelCase 183) Daily Challenge #189 - Convert Number into Reversed Array 184) Daily Challenge #190 - capitalizeFirstLast 185) Daily Challenge #191 - Alphabetical Addition 186) Daily Challenge #192 - Can you Survive the Zombies? 187) Daily Challenge #193 - What's the Real Floor? 188) Daily Challenge #194 - Spread Number 189) Daily Challenge #195 - No Zeroes for Heroes 190) Daily Challenge #196 - Flou 191) Daily Challenge #197 - Population Growth 192) Daily Challenge #198 - 21 Blackjack 193) Daily Challenge #199 - List of All Rationals 194) Daily Challenge #200 - Longest Linear Palindromic Substring 195) Daily Challenge #201 - Complete the Pattern 196) Daily Challenge #202 - Complete the Pattern II 197) Daily Challenge #203 - Pascal's Triangle 198) Daily Challenge #204 - Partial Keys 199) Daily Challenge #205 - Consonant String Value 200) Daily Challenge #206 - Pound Means Backspace 201) Daily Challenge #207 - Snakes and Ladders 202) Daily Challenge #208 - Delete Occurrences of an Element 203) Daily Challenge #209 - Roman Numerals 204) Daily Challenge #210 - Separate Capitalization 205) Daily Challenge #211 - Product Partitions 206) Daily Challenge #212 - DNA to RNA 207) Daily Challenge #213 - Are they the "same"? 208) Daily Challenge #214 - Persistent Bugger 209) Daily Challenge #215 - Difference of 2 210) Daily Challenge #216 - Rainfall 211) Daily Challenge #217 - SMS w/ an Old Phone 212) Daily Challenge #218 - Possible Sides of a Non-Right Triangle 213) Daily Challenge #219 - Compare Strings 214) Daily Challenge #220 - What Dominates Your Array? 215) Daily Challenge #221 - The Merchant of York 216) Daily Challenge #222 - Parse Bank Account Numbers 217) Daily Challenge #223 - Responsible Drinking 218) Daily Challenge #224 - Password Validator 219) Daily Challenge #225 - Square'n'Sum 220) Daily Challenge #226 - Array to HTML Table 221) Daily Challenge #227 - Android Lock Screen 222) Daily Challenge #228 - Best Profit in Single Sale 223) Daily Challenge #229 - Haiku Validator 224) Daily Challenge #230 - Beeramid 225) Daily Challenge #231 - Perfect Powers 226) Daily Challenge #232 - Regex Pattern 227) Daily Challenge #233 - Get Planet Name by ID 228) Daily Challenge #234 - Happy Birthday! 229) Daily Challenge #235 - Reversing a Process 230) Daily Challenge #236 - RGB to Hex Conversion 231) Daily Challenge #237 - Delete Extra Occurrences 232) Daily Challenge #238 - One is the Loneliest Number 233) Daily Challenge #239 - Graceful Tipping 234) Daily Challenge #240 - ATM 235) Daily Challenge #241 - Tip Calculator 236) Daily Challenge #242 - Expressions Matter 237) Daily Challenge #243 - Redacted! 238) Daily Challenge #244 - Search for Letters 239) Daily Challenge #245 - Sort Santa's Reindeer 240) Daily Challenge #246 - Readable Specification Pattern 241) Daily Challenge #247 - Get Planet Name By ID 242) Daily Challenge #248 - Chinese Numerals 243) Daily Challenge #249 - Incremental Changes 244) Daily Challenge #250 - Last Digit of a Large Number 245) Daily Challenge #251 - Largest Number in a Sequence 246) Daily Challenge #252 - Everybody hates Mondays 247) Daily Challenge #253 - Sort Sentences Pseudo-alphabetically 248) Daily Challenge #254 - The Vowel Code 249) Daily Challenge #255 - Is There an Odd Bit? 250) Daily Challenge #256 - How Many Are Smaller Than I? 251) Daily Challenge #257 - Halving Sum 252) Daily Challenge #258 - Ranking Poker Hands 253) Daily Challenge #259 - Duplicate Encoder 254) Daily Challenge #260 - Subtract the Sum 255) Daily Challenge #261 - Diagonal Strings 256) Daily Challenge #262 - No One Likes Spare Change 257) Daily Challenge #263 - Reverse Words 258) Daily Challenge #264 - Digital Root 259) Daily Challenge #265 - Equal Sides 260) Daily Challenge #266 - Who Likes It? 261) Daily Challenge #267 - Braking Speed 262) Daily Challenge #268 - Swapping Characters in Strings 263) Daily Challenge #269 - Decompose n! 264) Daily Challenge #270 - Fix String Case 265) Daily Challenge #271 - Simulate Population Growth 266) Daily Challenge #272 - Printer Errors 267) Daily Challenge #273 - Remove Duplicates 268) Daily Challenge #274 - Aerial Firefighting 269) Daily Challenge #275 - Casino Chips 270) Daily Challenge #276 - Unwanted Dollar Signs 271) Daily Challenge #277 - Over the Road 272) Daily Challenge #278 - Find all non-consecutive numbers 273) Daily Challenge #279 - Playing with Sandpiles

Today's challenge requires you to create a function that will take a float and return the amount formatted in dollars and cents.

For example: 6.2 becomes $6.20


Want to propose a challenge idea for a future post? Email yo+challenge@dev.to with your suggestions!

This challenge comes from kolohelios on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

Discussion

markdown guide
 

Here we go!

f=a=>`$${a.toFixed`2`}`;

And the results:

f(.4); // "$0.40"
f(0); // "$0.00"
f(6.2); // "$6.20"

And how about some Intl?

f=a=>new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(a)

Which does a bit more, like adding commas:

f(.4); // "$0.40"
f(0); // "$0.00"
f(6.2); // "$6.20"
f(100000000.1234); // "$100,000,000.12"
 

Hello, I am surprised, you can call a function with ``. How come is it working?

 

ES6 added this functionality, called Tagged Template! A few examples can be found here: wesbos.com/tagged-template-literals/

Thanks a ton :) learnt new thing

 

Sometimes I just think about Rails method that does a very specific thing, type it out in console and it works

number_to_currency(number)
 
const formatDollars = money => `$${money.toFixed(2)}`;


`
love js

 

Mind rounding "errors":

formatDollars(.126)
> '$0.13'

Same happens in python:

print(f"{123.126:.2f}")
123.13
 

It rounded up, though, so is that an error? It seems like expected behavior to me.

 

Go - with tests as usual

fun fact - this was the first time I wrote anything using Vim

dollars.go

package dollars

import (
    "fmt"
)

// Dollars returns the string representation of a float as a dollar amount
func Dollars(amount float64) string {
    return fmt.Sprintf("$%.2f", amount)
}

dollars_test.go

package dollars

import (
    "testing"
)

var testCases = []struct {
    description string
    input       float64
    expected    string
}{
    {
        "only cents",
        .04,
        "$0.04",
    },
    {
        "only dollars",
        3,
        "$3.00",
    },
    {
        "cents & dollars",
        3.14,
        "$3.14",
    },
    {
        "amounts with more than two decimal places round to the nearest cent",
        4.478,
        "$4.48",
    },

}

func TestDollars(t *testing.T) {
    for _, test := range testCases {
        if result := Dollars(test.input); result != test.expected {
            t.Fatalf("FAILED: %s - Dollars(%f): %s, expected %s \n", test.description, test.input, result, test.expected)
        }
        t.Logf("PASS: %s \n", test.description)
    }
}

 

I'm not sure, but I think that "Sprintf" rounds to nearest integer.
Try with a value like 3.149 if still returns 3.14 or 3.15

 

Added additional test case to clarify current rounding behavior.

 

Yeah it rounds to the nearest cent in this case, the question becomes then do we want it to work that way, or do we say "Hey you don't have a full cent" so it always rounds down?

 

With miles separator too:

const formatMoney = money => [...`$${money .toFixed(2)}`]
  .reverse()
  .flatMap((c, i) => (c != '.' && c != '$' && i > 3 && i % 3 == 0) ? [',', c]: [c])
  .reverse()
  .join('');

// formatMoney(12123123123131232.000) => $12,123,123,123,131,232.00
 

Here is the simple solution with PHP:

function format_money(float $amount): string {
    $amounts = explode('.', (string)$amount);
    $moneyFormat = '$%d.%s';

    if (count($amounts) === 1) {
        $floating = '00';

        return sprintf($moneyFormat, $amounts[0], $floating);
    }

    if (strlen($amounts[1]) === 1) {
      $floating = $amounts[1] . '0';

      return sprintf($moneyFormat, $amounts[0], $floating);
    }

    return sprintf($moneyFormat, $amounts[0], substr($amounts[1], 0, 2));
}
 

My take at the challenge written in Haskell.

toFloat :: String -> Float
toFloat string = read string :: Float

decimalToInt :: Float -> Int
decimalToInt float =
  round
    $ (*) 100
    $ toFloat
    $ take 5
    $ show
    $ float - (fromIntegral $ floor float)

decimalToDollar :: Float -> String
decimalToDollar float =
  "$" 
    ++ (show $ round float)
    ++ "."
    ++ (show $ decimalToInt float)

main :: IO ()
main = do
  putStrLn $ show $ decimalToDollar 6.2 -- "$6.20"
  putStrLn $ show $ decimalToDollar 6.227 -- "$6.23"

Try it online.

For some reason, I get imprecise floating point numbers when grabbing the decimal part of a floating point number in Haskell. I'm pretty new to this language so I must miss something. Feel free to improve my work here.

 

Rust Function:

fn format_dollar(price: f32) -> String {
    format!("${:.2}", price)
}
 
define_method(:us_curr) { |float| format('$%.2f', float.truncate(2)) }
us_curr 2.1256 # => "$2.12"

I thought about this problem from a financial standpoint and didn't like the default ruby or rails options that have been given so far because of how much lost revenue could be happening. Amazon for example has over a billion transactions a day (according to the first link on google). If we use 1.3 billion transactions and assume that the average fractional cents that they give up in a day of transactions is half a cent (.05). That would cost them 6.5 million dollars in lost revenue from giving up fractions of a cent. My solution just trims the number instead of rounding it.

I could see potential for wanting to round up from a business standpoint too, if the calculations are creating a price point for your product in a currency form then by all means you want to round up to still avoid that 6.5 million hit. In which case you would have to adjust the currency function.

This problem can really get interesting depending on your outlook.

 

Python :)

def to_currency(value: float) -> str:
    return "${:.2f}".format(value)

print(to_currency(6.2)) # $6.20
 

Python

print('$%.2f' %(float(input('Give me money '))))
 

Ruby

def maney(amount)
  "$" + '%.2f' % amount.to_f
end
 

Elixir:

defmodule Day49 do
  def float_to_money(float),
    do: "$#{:io_lib.format("~.2f", [float])}"
end
 

ruby <3

define_method(:format_dollar, &"$%.02f".:%)
 

Rust:

fn format_dollars(amount: f64) -> String {
    format!("${:.2}", amount)
}
 

Here is the python code

num=float(input())
print("${:,.2f}".format(num))