[lex.icon] (original) (raw)

5 Lexical conventions [lex]

5.13 Literals [lex.literal]

5.13.2 Integer literals [lex.icon]

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

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

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

decimal-literal: nonzero-digit decimal-literal ' 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 ' 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-suffix unsigned-suffix long-long-suffix long-suffix unsigned-suffix long-long-suffix unsigned-suffix

unsigned-suffix: one of u U

long-suffix: one of l L

long-long-suffix: one of ll LL

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

[ Note

:

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

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

[ Example

:

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

]

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

An integer-literal is a prvalue.

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

If an integer-literalcannot 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-literalare signed, the extended integer type shall be signed.

If all of the types in the list for the integer-literalare unsigned, the extended integer type shall be unsigned.

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

A program is ill-formed if one of its translation units contains an integer-literalthat cannot be represented by any of the allowed types.