Decimal integer constant: can only appear.
0~9
Numbers, and can be signed. take for example
1 1
Octal integer constant: in numbers
Octal digit string at the beginning, where the number is
0~7。 take for example
0 1 1 (decimal 9)
Hexadecimal integer constant: in
0x
or
0x
Hexadecimal digit string at the beginning, where each digit can be
0~9、a~f
or
a~
f
Numbers or English letters. take for example
0x 1 1 (decimal
17)