# 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
```
```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:
```
```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: 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
long-suffix unsigned-suffixopt
long-long-suffix unsigned-suffixopt
```
```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 of binary-digits, octal-digits, digits, or hexadecimal-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-digits a through f and A through F have 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, and 0'004'000'000 all have the same value.
— end example
]
The type of an integer-literal is the first type in the list in Table 8 corresponding to its optional integer-suffix in 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-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 shall be signed.
If all of the types in the list for the integer-literal are 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-literal that cannot be represented by any of the allowed types.