1. Octa-made constant eight-feed immologists must begin with 0, that is, 0 as a prefix of the eight-input number. The digital value is 0 to 7. The number of octaves is usually unsigned. The following numbers are legal octaves: 015 (decimal 13) 0101 (decimal 65) 0177777 (decimal 65535) The following number is not legal octal number: 256 (unprogin 0) 03A2 (including non-eight-way digital digital) -0127 (there is a negative sign) 2. The prefix of the hexadecimal rectification of 16-year-in constant is 0x or 0x. Its digital value is 0 ~ 9, A ~ f or A ~ F. The following numbers are legally hexadecimal impromptus: 0x2a (decimal 42) 0xA0 (decimal 160) 0xFFF (decimal 65535) The following number is not a legal hexadecimal general number: 5A (unproped 0x) 0x3H (containing non-heteo-binary digital) 3. Decoction finite millive incoming constant has no prefix. Its digital is 0 ~ 9. The following numbers are legal decimal usual numbers: 237 -568 65535 1627 The following number is not a legal decimal general number: 023 (not a preamble 0) 23d (including non-ten-way digital) is based on the prefix in the program to distinguish various kinds Counting. Therefore, don't make the prefix correctly when writing constants is incorrect. 4. The suffix of the integer constant is on the 16-bit word long, the basic integer is also 16 bits, so the scope of the number indicated is also limited. The decimal number of endless symbols is from 0 to 65535, and the number of symbols is -32768 ~ 32767. The representation of the octal unsigned number is 0 ~ 0177777. The hexadecimal non-symbolic number of representations is 0x0 ~ 0xFFFF or 0x0 ~ 0xFFFF. If the number of uses exceeds the above range, it must be represented by long integer. Long integer is represented by suffix "L" or "L". For example: decimal length is 158L (decimal 158) 358000L (decimal is -358000) octal long improvement 012L (decimal 10) 077L (decimal 63) 0200000L (decimal 65536) hexadecimal length often 0x15L ( Teconation 21) 0xA5L (decimal 165) 0x10000L (decimal 65536) Long integer 158L and basic completion 158 There is no difference in value. But to 158L, because the C-compilation system will allocate 4 byte storage space for it. For 158, since it is basically integrated, only 2 bytes of storage space is allocated. Therefore, pay attention to the operation and output format, avoid errors. No symbol numbers can also be represented by the suffix, the suffix of unsigned number of integer constants is "U" or "U". For example: 358U, 0x38au, 235lu are both unsigned. Prefix, suffix can be used simultaneously to represent various types of numbers. If 0xA5lu means hexadecimal unsigned long integer A5, its decimal is 165. The escape character escape character is a special character constant. The escape character begins with a backslash "/", followed by one or a few characters. The escape character has a specific meaning, different from the original meaning of characters, so that "escape" characters. For example, "/ n" used in the format string of the previous example Printf function is a escape character, and its meaning is "Enter the Running Wrap". The escape character is primarily used to indicate those control code that is inconvenient to use in general characters.
