C Integer Constants
An integer constant is a decimal (base 10), octal (base 8), or hexadecimal (base 16) number that represents an integral value. Use integer constants to represent integer values that can't be changed.
Syntax
integer-constant:
decimal-constant integer-suffixopt
octal-constant integer-suffixopt
hexadecimal-constant integer-suffixopt
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-suffixopt
unsigned-suffix long-long-suffix
unsigned-suffix 64-bit-integer-suffix
long-suffix unsigned-suffixopt
long-long-suffix unsigned-suffixopt
64-bit-integer-suffix
unsigned-suffix: one of
u U
long-suffix: one of
l L
long-long-suffix: one of
ll LL
64-bit-integer-suffix: one of
i64 I64
The i64 and I64 suffixes are Microsoft-specific.
Integer constants are positive unless they're preceded by a minus sign (-). The minus sign is interpreted as the unary arithmetic negation operator. (See Unary Arithmetic Operators for information about this operator.)
If an integer constant begins with 0x or 0X, it's hexadecimal. If it begins with the digit 0, it's octal. Otherwise, it's assumed to be decimal.
The following integer constants are equivalent:
28
0x1C /* = Hexadecimal representation for decimal 28 */
034 /* = Octal representation for decimal 28 */
No white-space characters can separate the digits of an integer constant. These examples show some valid decimal, octal, and hexadecimal constants.
/* Decimal Constants */
int dec_int = 28;
unsigned dec_uint = 4000000024u;
long dec_long = 2000000022l;
unsigned long dec_ulong = 4000000000ul;
long long dec_llong = 9000000000LL;
unsigned long long dec_ullong = 900000000001ull;
__int64 dec_i64 = 9000000000002I64;
unsigned __int64 dec_ui64 = 90000000000004ui64;
/* Octal Constants */
int oct_int = 024;
unsigned oct_uint = 04000000024u;
long oct_long = 02000000022l;
unsigned long oct_ulong = 04000000000UL;
long long oct_llong = 044000000000000ll;
unsigned long long oct_ullong = 044400000000000001Ull;
__int64 oct_i64 = 04444000000000000002i64;
unsigned __int64 oct_ui64 = 04444000000000000004uI64;
/* Hexadecimal Constants */
int hex_int = 0x2a;
unsigned hex_uint = 0XA0000024u;
long hex_long = 0x20000022l;
unsigned long hex_ulong = 0XA0000021uL;
long long hex_llong = 0x8a000000000000ll;
unsigned long long hex_ullong = 0x8A40000000000010uLL;
__int64 hex_i64 = 0x4a44000000000020I64;
unsigned __int64 hex_ui64 = 0x8a44000000000040Ui64;