Because the memory (DRAM, SRAM, Flash, hard disk) and operators in a computer all work on a binary basis, the data representation itself should be binary.

But the binary representation of data is too inefficient, a 32-bit integer should be written as 0000 0000 0000 0000 0000 0000 0000 0000 0011 this kind of appearance, neither easy to read, nor easy to remember.

So I want to use other methods to indicate that the 10-bit conversion is troublesome, and there is no correspondence by bit, hexadecimal is better, just four binary corresponds to a hexadecimal, so an integer is expressed as a 0x00000003 this way it is much more convenient, 0x is a fixed representation of the hexadecimal with the beginning of the.