.TH "Char.Ascii" 3 2025-06-09 OCamldoc "OCaml library"
.SH NAME
Char.Ascii \- ASCII character set support.
.SH Module
Module   Char.Ascii
.SH Documentation
.sp
Module
.BI "Ascii"
 : 
.B sig end

.sp
ASCII character set support\&.
.sp
These functions give meaning to the integers [
.ft B
0x00
.ft R
;
.ft B
0x7F
.ft R
] of the
ASCII
character set\&.
.sp
Since the UTF\-8 encoding of Unicode has the same encoding and
character semantics (U+0000 to U+001F) for these bytes, the
functions can be safely used on elements of UTF\-8 encoded 
.ft B
string
.ft R
and 
.ft B
bytes
.ft R
values\&. However the functions only deal with ASCII
related matters\&. For example the notion of Unicode whitespace is
much larger than the ASCII whitespace determined by
.ft B
Char\&.Ascii\&.is_white
.ft R
\&.

.sp
.B "Since"
5.4

.sp

.sp
.sp

.PP
.SS Characters

.PP

.I val min 
: 
.B char
.sp

.ft B
min
.ft R
is 
.ft B
\&'\(rsx00\&'
.ft R
\&.

.sp

.I val max 
: 
.B char
.sp

.ft B
max
.ft R
is 
.ft B
\&'\(rsx7F\&'
.ft R
\&.

.sp

.PP
.SS Predicates

.PP

.I val is_valid 
: 
.B char -> bool
.sp

.ft B
is_valid c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII character,
that is a byte in the range [
.ft B
Char\&.Ascii\&.min
.ft R
;
.ft B
Char\&.Ascii\&.max
.ft R
]\&.

.sp

.I val is_upper 
: 
.B char -> bool
.sp

.ft B
is_upper c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII uppercase letter
.ft B
\&'A\&'
.ft R
to 
.ft B
\&'Z\&'
.ft R
, that is a byte in the range [
.ft B
0x41
.ft R
;
.ft B
0x5A
.ft R
]\&.

.sp

.I val is_lower 
: 
.B char -> bool
.sp

.ft B
is_lower c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII lowercase letter
.ft B
\&'a\&'
.ft R
to 
.ft B
\&'z\&'
.ft R
, that is a byte in the range [
.ft B
0x61
.ft R
;
.ft B
0x7A
.ft R
]\&.

.sp

.I val is_letter 
: 
.B char -> bool
.sp

.ft B
is_letter c
.ft R
is 
.ft B
Char\&.Ascii\&.is_lower
.ft R
.ft B
c || 
.ft R
.ft B
Char\&.Ascii\&.is_upper
.ft R
.ft B
c
.ft R
\&.

.sp

.I val is_alphanum 
: 
.B char -> bool
.sp

.ft B
is_alphanum c
.ft R
is 
.ft B
Char\&.Ascii\&.is_letter
.ft R
.ft B
c || 
.ft R
.ft B
Char\&.Ascii\&.is_digit
.ft R
.ft B
c
.ft R
\&.

.sp

.I val is_white 
: 
.B char -> bool
.sp

.ft B
is_white c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII white space
character, that is one of
tab 
.ft B
\&'\(rst\&'
.ft R
(
.ft B
0x09
.ft R
), newline 
.ft B
\&'\(rsn\&'
.ft R
(
.ft B
0x0A
.ft R
),
vertical tab (
.ft B
0x0B
.ft R
), form feed (
.ft B
0x0C
.ft R
),
carriage return 
.ft B
\&'\(rsr\&'
.ft R
(
.ft B
0x0D
.ft R
) or space 
.ft B
\&' \&'
.ft R
(
.ft B
0x20
.ft R
),

.sp

.I val is_blank 
: 
.B char -> bool
.sp

.ft B
is_blank c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII blank character,
that is either space 
.ft B
\&' \&'
.ft R
(
.ft B
0x20
.ft R
) or tab 
.ft B
\&'\(rst\&'
.ft R
(
.ft B
0x09
.ft R
)\&.

.sp

.I val is_graphic 
: 
.B char -> bool
.sp

.ft B
is_graphic c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII graphic
character, that is a byte in the range [
.ft B
0x21
.ft R
;
.ft B
0x7E
.ft R
]\&.

.sp

.I val is_print 
: 
.B char -> bool
.sp

.ft B
is_print c
.ft R
is 
.ft B
Char\&.Ascii\&.is_graphic
.ft R
.ft B
c || c = \&' \&'
.ft R
\&.

.sp

.I val is_control 
: 
.B char -> bool
.sp

.ft B
is_control c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII control character,
that is a byte in the range [
.ft B
0x00
.ft R
;
.ft B
0x1F
.ft R
] or 
.ft B
0x7F
.ft R
\&.

.sp

.PP
.SS Decimal digits

.PP

.I val is_digit 
: 
.B char -> bool
.sp

.ft B
is_digit c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII decimal digit
.ft B
\&'0\&'
.ft R
to 
.ft B
\&'9\&'
.ft R
, that is a byte in the range [
.ft B
0x30
.ft R
;
.ft B
0x39
.ft R
]\&.

.sp

.I val digit_to_int 
: 
.B char -> int
.sp

.ft B
digit_to_int c
.ft R
is the numerical value of a digit
that satisfies 
.ft B
Char\&.Ascii\&.is_digit
.ft R
\&. Raises 
.ft B
Invalid_argument
.ft R
if
.ft B
Char\&.Ascii\&.is_digit
.ft R
.ft B
c
.ft R
is 
.ft B
false
.ft R
\&.

.sp

.I val digit_of_int 
: 
.B int -> char
.sp

.ft B
digit_of_int n
.ft R
is an ASCII decimal digit for the decimal
value 
.ft B
abs (n mod 10)
.ft R
\&.

.sp

.PP
.SS Hexadecimal digits

.PP

.I val is_hex_digit 
: 
.B char -> bool
.sp

.ft B
is_hex_digit c
.ft R
is 
.ft B
true
.ft R
if and only if 
.ft B
c
.ft R
is an ASCII hexadecimal
digit 
.ft B
\&'0\&'
.ft R
to 
.ft B
\&'9\&'
.ft R
, 
.ft B
\&'a\&'
.ft R
to 
.ft B
\&'f\&'
.ft R
or 
.ft B
\&'A\&'
.ft R
to 
.ft B
\&'F\&'
.ft R
,
that is a byte in one of the ranges [
.ft B
0x30
.ft R
;
.ft B
0x39
.ft R
],
[
.ft B
0x41
.ft R
;
.ft B
0x46
.ft R
], [
.ft B
0x61
.ft R
;
.ft B
0x66
.ft R
]\&.

.sp

.I val hex_digit_to_int 
: 
.B char -> int
.sp

.ft B
hex_digit_to_int c
.ft R
is the numerical value of a digit that
satisfies 
.ft B
Char\&.Ascii\&.is_hex_digit
.ft R
\&. Raises 
.ft B
Invalid_argument
.ft R
if
.ft B
Char\&.Ascii\&.is_hex_digit
.ft R
.ft B
c
.ft R
is 
.ft B
false
.ft R
\&.

.sp

.I val lower_hex_digit_of_int 
: 
.B int -> char
.sp

.ft B
lower_hex_digit_of_int n
.ft R
is a lowercase ASCII hexadecimal digit for
the hexadecimal value 
.ft B
abs (n mod 16)
.ft R
\&.

.sp

.I val upper_hex_digit_of_int 
: 
.B int -> char
.sp

.ft B
upper_hex_digit_of_int n
.ft R
is an uppercase ASCII hexadecimal
digit for the hexadecimal value 
.ft B
abs (n mod 16)
.ft R
\&.

.sp

.PP
.SS Casing transforms

.PP

.I val uppercase 
: 
.B char -> char
.sp

.ft B
uppercase c
.ft R
is 
.ft B
c
.ft R
with ASCII characters 
.ft B
\&'a\&'
.ft R
to 
.ft B
\&'z\&'
.ft R
respectively
mapped to uppercase characters 
.ft B
\&'A\&'
.ft R
to 
.ft B
\&'Z\&'
.ft R
\&. Other characters are left
untouched\&.

.sp

.I val lowercase 
: 
.B char -> char
.sp

.ft B
lowercase c
.ft R
is 
.ft B
c
.ft R
with ASCII characters 
.ft B
\&'A\&'
.ft R
to 
.ft B
\&'Z\&'
.ft R
respectively
mapped to lowercase characters 
.ft B
\&'a\&'
.ft R
to 
.ft B
\&'z\&'
.ft R
\&. Other characters are
left untouched\&.

.sp