Python 内置函数进制转换的用法(十进制转二进制、八进制、十

使用Python内置函数：bin()、oct()、int()、hex()可实现进制转换。
先看Python官方文档中对这几个内置函数的描述：
bin(x)
Convert an integer number to a binary string. The result is a valid Python expression. If x is not a Python int object, it has to define an index() method that returns an integer.

oct(x)
Convert an integer number to an octal string. The result is a valid Python expression. If x is not a Python int object, it has to define an index() method that returns an integer.

int([number | string[, base]])
Convert a number or string to an integer. If no arguments are given, return 0. If a number is given, return number.int(). Conversion of floating point numbers to integers truncates towards zero. A string must be a base-radix integer literal optionally preceded by ‘+' or ‘-‘ (with no space in between) and optionally surrounded by whitespace. A base-n literal consists of the digits 0 to n-1, with ‘a' to ‘z' (or ‘A' to ‘Z') having values 10 to 35. The default base is 10. The allowed values are 0 and 2-36. Base-2, -8, and -16 literals can be optionally prefixed with 0b/0B, 0o/0O, or 0x/0X, as with integer literals in code. Base 0 means to interpret exactly as a code literal, so that the actual base is 2, 8, 10, or 16, and so that int('010', 0) is not legal, while int('010') is, as well as int('010', 8).

hex(x)
Convert an integer number to a hexadecimal string. The result is a valid Python expression. If x is not a Python int object, it has to define an index() method that returns an integer.

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bin()、oct()、hex()的返回值均为字符串，且分别带有0b、0o、0x前缀。

import os,sys
 
# global definition
# base = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F]
base = [str(x) for x in range(10)] + [ chr(x) for x in range(ord('A'),ord('A')+6)]
 
# bin2dec
# 二进制 to 十进制: int(str,n=10) 
def bin2dec(string_num):
 return str(int(string_num, 2))
 
# hex2dec
# 十六进制 to 十进制
def hex2dec(string_num):
 return str(int(string_num.upper(), 16))
 
# dec2bin
# 十进制 to 二进制: bin() 
def dec2bin(string_num):
 num = int(string_num)
 mid = []
 while True:
 if num == 0: break
 num,rem = divmod(num, 2)
 mid.append(base[rem])
 
 return ''.join([str(x) for x in mid[::-1]])
 
# dec2hex
# 十进制 to 八进制: oct() 
# 十进制 to 十六进制: hex() 
def dec2hex(string_num):
 num = int(string_num)
 mid = []
 while True:
 if num == 0: break
 num,rem = divmod(num, 16)
 mid.append(base[rem])
 
 return ''.join([str(x) for x in mid[::-1]])
 
# hex2tobin
# 十六进制 to 二进制: bin(int(str,16)) 
def hex2bin(string_num):
 return dec2bin(hex2dec(string_num.upper()))
 
# bin2hex
# 二进制 to 十六进制: hex(int(str,2)) 
def bin2hex(string_num):
 return dec2hex(bin2dec(string_num))