CODEWITHSUNDEEP
stringhaskell
Zhen
Zhen

Reputation: 4283

Haskell printf to string

Is there a sprintf equivalent in Haskell?

I need to convert and format double values into strings.

Is there another way without using printf kind of functions?

The main problem is to avoid:

Prelude> putStrLn myDoubleVal
1.7944444444444447e-2

Instead, I want this:

Prelude> putStrLn . sprintf "%.2f" $ myDoubleVal
1.79

Upvotes: 22

Views: 9787

Answers (3)

ynishi
ynishi

Reputation: 326

Formatting is an option to create formatted string, if you want '"s"printf' and don't need full compatibility with printf style.

Upvotes: 0

Chris Taylor
Chris Taylor

Reputation: 47382

Yes, it's in the Text.Printf module, and it's just called printf.

> import Text.Printf
> let x = 1.14907259
> putStrLn . printf "%.2f" $ x
1.15

Note that the return type of printf is overloaded, so that it's capable of returning a String (as in the example above) but it's also capable of returning an I/O action that does the printing, so you don't actually need the call to putStrLn:

> printf "%.2f\n" x
1.15

Upvotes: 55

swpd
swpd

Reputation: 1151

Text.Printf might be what you need.

Upvotes: 3

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