Character

Check if a value is a character

Given a file named “main.scm” with:

(import (scheme base))

(write-u8 (if (char? <expression>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

expression
#\A
#\newline
(integer->char 65)

Check an alphabetic character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-alphabetic? #\<value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
a	A
A	A
z	A
Z	A
À	A
Ý	A
ß	A
ß	A
à	A
ý	A
Α	A
α	A
あ	A
を	A
@	B
0	B

Check a character of other alphabetic

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-alphabetic? (integer->char <value>)) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
837	A
113822	A
127369	A

Check a numeric character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-numeric? #\<value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
0	A
9	A
@	B
A	B

Check a lower case character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-lower-case? #\<value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
0	B
9	B
@	B
a	A
A	B
z	A
Z	B
ẞ	B
À	B
Ý	B
ß	A
à	A
ý	A
α	A

Check a upper case character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-upper-case? #\<value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
0	B
9	B
@	B
A	A
a	B
Z	A
z	B
ẞ	A
À	A
Ý	A
ß	B
à	B
ý	B
α	B

Check a whitespace character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (char-whitespace? <expression>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

expression	output
#\newline	A
#\return	A
#\space	A
#\tab	A
#@	B
#\A	B
(integer->char 12288)	A

Write a character

Given a file named “main.scm” with:

(import (scheme base))

(write-char #\A)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Write a newline character

Given a file named “main.scm” with:

(import (scheme base))

(write-char #\A)
(newline)
(write-char #\B)

When I successfully run stak main.scm

Then the stdout should contain exactly:

A
B

Compare characters

Given a file named “main.scm” with:

(import (scheme base))

(write-u8 (if (<predicate> <characters>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

predicate	characters	output
char=?	#\A #\A	A
char=?	#\A #\B	B
char=?	#\A #\A #\A	A
char=?	#\A #\A #\B	B
char<?	#\A #\B	A
char<?	#\A #\A	B
char<?	#\B #\A	B
char<?	#\A #\B #\C	A
char<?	#\A #\B #\B	B
char<=?	#\A #\B	A
char<=?	#\A #\A	A
char<=?	#\B #\A	B
char<=?	#\A #\B #\C	A
char<=?	#\A #\B #\B	A

Compare case-insensitive characters

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (<predicate> <characters>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

predicate	characters	output
char-ci=?	#\A #\A	A
char-ci=?	#\a #\A	A
char-ci=?	#\A #\B	B

Convert a character to its lower case

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (eqv? (char-downcase <input>) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
#@	#@
#\A	#\a
#\a	#\a
#\Z	#\z
#\z	#\z
#\ẞ	#\ß
#\µ	#\µ
#\Α	#\α
#\ſt	#\ſt

Convert a character to its upper case

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (eqv? (char-upcase <input>) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
#@	#@
#\a	#\A
#\A	#\A
#\z	#\Z
#\Z	#\Z
#\α	#\Α

input	output
#\ß	#\ß

Fold a character

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (equal? (char-foldcase <input>) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
#@	#@
#[	#[
#`	#`
#\A	#\a
#\a	#\a
#\Z	#\z
#\z	#\z
#{	#{
#\µ	#\μ
#\À	#\à
#\Ý	#\ý
#\ß	#\ß
#\Ꟶ	#\ꟶ
#\Α	#\α

input	output
#\ſt	#\st

input	output
#\𞤀	#\𞤢
#\𞤡	#\𞥃

Extract a digit value

Given a file named “main.scm” with:

(import (scheme base) (scheme char))

(write-u8 (if (= (digit-value #\<character>) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

character	output
0	0
1	1
6	6
9	9