6.4.4.1 Integer constants

integer-constant:
                decimal-constant integer-suffix_opt
                octal-constant integer-suffix_opt
                hexadecimal-constant integer-suffix_opt

decimal-constant:
                nonzero-digit
                decimal-constant digit

octal-constant:
                0
                octal-constant octal-digit

hexadecimal-constant:
                hexadecimal-prefix hexadecimal-digit
                hexadecimal-constant hexadecimal-digit

hexadecimal-prefix: one of
                0x  0X

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

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

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_opt
                unsigned-suffix long-long-suffix
                long-suffix unsigned-suffix_opt
                long-long-suffix unsigned-suffix_opt

unsigned-suffix: one of
                u  U

long-suffix: one of
                l  L

long-long-suffix: one of
                ll  LL

821 An integer constant begins with a digit, but has no period or exponent part.

822 It may have a prefix that specifies its base and a suffix that specifies its type.

823 A decimal constant begins with a nonzero digit and consists of a sequence of decimal digits.

824 An octal constant consists of the prefix 0 optionally followed by a sequence of the digits 0 through 7 only.

825 A hexadecimal constant consists of the prefix 0x or 0X followed by a sequence of the decimal digits and the letters a (or A) through f (or F) with values 10 through 15 respectively.

826 The value of a decimal constant is computed base 10;

827 that of an octal constant, base 8;

828 that of a hexadecimal constant, base 16.

829 The lexically first digit is the most significant.

830 The type of an integer constant is the first of the corresponding list in which its value can be represented.

831 .TABLE : l l l Suffix , Decimal Constant , Octal or Hexadecimal Constant

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 , , .E_TABLE

832 If an integer constant cannot be represented by any type in its list, it may have an extended integer type, if the extended integer type can represent its value.

833 If all of the types in the list for the constant are signed, the extended integer type shall be signed.

834 If all of the types in the list for the constant are unsigned, the extended integer type shall be unsigned.

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