Integer literals are used to write values of types int , uint , long , and ulong . Integer literals have two possible forms: decimal and hexadecimal.

integer-literal

decimal-integer-literal

hexadecimal-integer-literal

decimal-integer-literal

decimal-digits integer-type-suffix_opt

decimal-digit

decimal-digit

decimal-digits decimal-digit

decimal-digit

0 1 2 3 4 5 6 7 8 9

integer-type-suffix

U u L l UL Ul uL ul LU Lu lU lu

hexadecimal-integer-literal

0x hex-digits integer-type-suffix_opt

0X hex-digits integer-type-suffix_opt

hex-digit

hex-digit

hex-digits hex-digit

hex-digit

0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f

The type of an integer literal is determined as follows:

• If the literal has no suffix, it has the first of these types in which its value can be represented: int , uint , long , ulong .
• If the literal is suffixed by U or u, it has the first of these types in which its value can be represented: uint , ulong .
• If the literal is suffixed by L or l, it has the first of these types in which its value can be represented: long , ulong .
• If the literal is suffixed by UL, Ul, uL, ul, LU, Lu, lU, or lu, it is of type ulong .

If the value represented by an integer literal is outside the range of the ulong type, a compile-time error occurs.

[Note: As a matter of style, it is suggested that "L" be used instead of "l" when writing literals of type long , since it is easy to confuse the letter "l" with the digit "1". end note]

To permit the smallest possible int and long values to be written as decimal integer literals, the following two rules exist:

• When a decimal-integer-literal with the value 2147483648 (231) and no integer-type-suffix appears as the token immediately following a unary minus operator token (14.6.2), the result is a constant of type int with the value 87222147483648 (8722231). In all other situations, such a decimal-integer-literal is of type uint .
• When a decimal-integer-literal with the value 9223372036854775808 (263) and no integer-type-suffix or the integer-type-suffix L or l appears as the token immediately following a unary minus operator token (14.6.2), the result is a constant of type long with the value 87229223372036854775808 (8722263). In all other situations, such a decimal-integer-literal is of type ulong .