digit-value(3scm)

✨ digit-value — Scheme Programmer’s Manual cutie 💅

okay so bestie, this is the digit-value page from the Scheme Programmer’s Manual, manual name 3scm — she’s tiny but she knows exactly one job. 🎀

💖 NAME

digit-value — get the numeric value of a character. literally the whole gig, no cap. ✨

📚 LIBRARY

R7RS girlies import it like this:

(import (scheme char))              ;R7RS

🧚 SYNOPSIS

(digit-value char)

🌸 DESCRIPTION

This procedure returns the numeric value of its argument if it is a numeric digit or #f on any other character. Numeric digits are those for which char-numeric? returns #t. Only the numeric values 0 to 9 are supported; characters representing other values are non-numeric. So like… digit? value. not digit? #f. simple as that, periodt. 💅

🦋 RETURN VALUES

Returns a single value; an exact integer or #f. one value only, bestie — exact integer or #f, no extras. 🫶

🔥 EXAMPLES

vibe check, look:

(digit-value #\3)      =>  3
(digit-value #\x0664)  =>  4    ;if supported
(digit-value #\x0AE6)  =>  0    ;if supported
(digit-value #\x0EA6)  =>  #f   ;if supported

🌈 COMPATIBILITY

Implementations are not required to support characters other than ASCII (excluding #\null). Therefore only the characters #\0 to #\9 need to be supported. Even implementations with full Unicode support may return #f for some characters that other implementations support, because the Unicode standard changes over time.

🫶 so true bestie: don’t assume every Unicode character is gonna hit the same in every implementation. the standard be moving.

💀 ERRORS

It is an error if the wrong number of arguments was passed or an argument was outside its domain. Implementations may signal an error, extend the procedure’s domain of definition to include such arguments, or fail catastrophically.

⚠️ “fail catastrophically” is literally right there in the manual. not me being dramatic. 💀

👑 SEE ALSO

• string->number(3scm)
• char-general-category(3scm)
• char-numeric?(3scm)

🌟 STANDARDS

R7RS. iconic. ✨

🕰️ HISTORY

This procedure first appeared in R7RS. yes she’s an R7RS baby. 🎀

💜 AUTHORS

This page is part of the scheme-manpages project. It includes materials from the RnRS documents. More information can be found at https://github.com/schemedoc/manpages/.

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mwah 💋 — this is digit-value(3scm) from the Scheme Programmer’s Manual, dated 2023-03-21, part of the scheme-manpages project. byeee, go get those numeric digits 🫶✨