If it is octal, it is the first 0, but the radix in octal is only 0-7. In C language, integer constants are expressed in octal, 10 and 16. Constants starting with 0, such as 0112,0531,are expressed in octal, and those starting with 0X or 0x are expressed in hexadecimal 16, such as 0x 12, 0xABC, without any prefix.

Octal

(radix 8) notation is very common in computer systems, so people can sometimes see octal notation. Because one bit of hexadecimal can correspond to four binary digits, it is more convenient to represent binary in hexadecimal. Therefore, octal application is not as good as hexadecimal. Some programming languages provide the ability to use octal symbols to represent numbers, but there are still some older Unix applications that use octal symbols.