cppdraft_translate/cppdraft/lex/icon.md

[lex.icon]

5 Lexical conventions [lex]

5.13 Literals [lex.literal]

5.13.2 Integer literals [lex.icon]

integer-literal:
binary-literal integer-suffixopt
octal-literal integer-suffixopt
decimal-literal integer-suffixopt
hexadecimal-literal integer-suffixopt

binary-literal:
0b binary-digit
0B binary-digit
binary-literal 'opt binary-digit

octal-literal:
0
octal-literal 'opt octal-digit

decimal-literal:
nonzero-digit
decimal-literal 'opt digit

hexadecimal-literal:
hexadecimal-prefix hexadecimal-digit-sequence

binary-digit: one of
0 1

octal-digit: one of
0 1 2 3 4 5 6 7

nonzero-digit: one of
1 2 3 4 5 6 7 8 9

hexadecimal-prefix: one of
0x 0X

hexadecimal-digit-sequence:
hexadecimal-digit
hexadecimal-digit-sequence 'opt hexadecimal-digit

hexadecimal-digit: one of
0 1 2 3 4 5 6 7 8 9
a b c d e f
A B C D E F

integer-suffix:
unsigned-suffix long-suffixopt
unsigned-suffix long-long-suffixopt
unsigned-suffix size-suffixopt
long-suffix unsigned-suffixopt
long-long-suffix unsigned-suffixopt
size-suffix unsigned-suffixopt

unsigned-suffix: one of
u U

long-suffix: one of
l L

long-long-suffix: one of
ll LL

size-suffix: one of
z Z

1

#

In an integer-literal, the sequence ofbinary-digits,octal-digits,digits, orhexadecimal-digits is interpreted as a base N integer as shown in Table 7; the lexically first digit of the sequence of digits is the most significant.

[Note 1:

The prefix and any optional separating single quotes are ignored when determining the value.

— end note]

Table 7 — Base of integer-literals [tab:lex.icon.base]

🔗 Kind of integer-literal	base N
🔗 binary-literal	2
🔗 octal-literal	8
🔗 decimal-literal	10
🔗 hexadecimal-literal	16

2

#

The hexadecimal-digitsa through f and A through F have decimal values ten through fifteen.

[Example 1:

The number twelve can be written 12, 014,0XC, or 0b1100.

The integer-literals 1048576,1'048'576, 0X100000, 0x10'0000, and0'004'000'000 all have the same value.

— end example]

3

#

The type of an integer-literal is the first type in the list in Table 8 corresponding to its optional integer-suffix in which its value can be represented.

Table 8 — Types of integer-literals [tab:lex.icon.type]

🔗 integer-suffix	decimal-literal	integer-literal other than decimal-literal
🔗 none	int	int
🔗	long int	unsigned int
🔗	long long int	long int
🔗		unsigned long int
🔗		long long int
🔗		unsigned long long int
🔗 u or U	unsigned int	unsigned int
🔗	unsigned long int	unsigned long int
🔗	unsigned long long int	unsigned long long int
🔗 l or L	long int	long int
🔗	long long int	unsigned long int
🔗		long long int
🔗		unsigned long long int
🔗 Both u or U	unsigned long int	unsigned long int
🔗 and l or L	unsigned long long int	unsigned long long int
🔗 ll or LL	long long int	long long int
🔗		unsigned long long int
🔗 Both u or U	unsigned long long int	unsigned long long int
🔗 and ll or LL
🔗 z or Z	the signed integer type corresponding	the signed integer type
🔗	to std​::​size_t ([support.types.layout])	corresponding to std​::​size_t
🔗		std​::​size_t
🔗 Both u or U	std​::​size_t	std​::​size_t
🔗 and z or Z

4

#

Except for integer-literals containing a size-suffix, if the value of an integer-literal cannot be represented by any type in its list and an extended integer type ([basic.fundamental]) can represent its value, it may have that extended integer type.

If all of the types in the list for the integer-literal are signed, the extended integer type is signed.

If all of the types in the list for the integer-literal are unsigned, the extended integer type is unsigned.

If the list contains both signed and unsigned types, the extended integer type may be signed or unsigned.

If an integer-literal cannot be represented by any of the allowed types, the program is ill-formed.

[Note 2:

An integer-literal with a z or Z suffix is ill-formed if it cannot be represented by std​::​size_t.

— end note]