使用Python二进制与十进制之间的转化，可以操作浮点数！

# coding=UTF-8
from decimal import Decimal
def mybin(float, bit = 10):
"""
这个程序用来将十进制数转化为二进制数,也可以转化浮点数
用法: mybin(float, bit=10)
float是指要转化的十进制数，可以为浮点数
bit是用来指定小数点后面的位数，默认为10位。
函数返回字符串
"""
## 看数据是否有效
#import types
#if type(float) is not types.IntType and type(float) is not types.FloatType:
#print "Error,Please check your input./n"
#return False
# 检测极性
negative = 0
if float < 0:
negative = 1
float = -1 * float
integer = int(float)                        # 整数部分
decimal = Decimal(str(float)) - integer     # 小数部分
integer_convert = ""         # 转化后的整数部分
decimal_convert = ""         # 转化后的小数部分
binary = ""                  # 最后的二进制数

if integer == 0:
binary = "0"
else:
while integer != 0:
result = int(integer % 2)
integer = integer / 2
integer_convert = str(result) + integer_convert
if decimal == 0:
binary = integer_convert
else:
i = 0
while decimal != 0 and i < bit:
result = int(decimal * 2)
decimal = decimal * 2 - result
decimal_convert = decimal_convert + str(result)
i = i + 1
binary = integer_convert + '.' + decimal_convert

if negative == 1:
binary = '-' + binary
return binary
def mydec(binary):
"""
将二进制数变成十进制数，包括浮点数
用法：mydec(binary)
binary是一个字符型二进制数，可以是浮点数
返回一个浮点数或者整数
"""
## 检测数据有效性
#if binary.find('-') not in [-1,0]:
#print binary + "/t>>>/t" + "Error with negative symbol's place./n"
#return False
#elif binary.find('.') != binary.rfind('.') or binary[0] == '.' or binary[-1] == '.'  or (binary.find('-') == 0 and binary.find('.') == 1 ):
#print binary + "/t>>>/t" + "Error with dot./n"
#return False
#else:
#for i in binary:
#if i not in ['1','0','-','.']:
#print binary + "/t>>>/t" + "Error, your number can only has /"1 0 - ./" symbols./n"
#return False
#检测极性
negative = 0
if binary[0] == '-':
negative = 1
binary = binary[1:]
integer = ""
decimal = ""
dot = binary.find('.')
if dot == -1:
integer = binary
else:
integer = binary[:dot]
decimal = binary[dot+1:]

cnt1=integer.__len__()
cnt2=decimal.__len__()
if cnt1 != 0:
temp = 0
index_reverse = range(0,cnt1)
for i in index_reverse:
temp = temp + int(integer[i]) * ( 2 ** (cnt1 - i - 1) )
integer = temp
else:
integer = 0
if cnt2 != 0:
temp = 0
index = range(1,cnt1+1)
for i in index:
temp = temp + int(decimal[ i-1 ]) * (2 ** (-1*i))
decimal = temp
else:
decimal = 0

result = integer + decimal
if negative == 1:
result = -1 * result

return result

###########################
# Test Part
###########################
if __name__=="__main__":
print "测试1-- mybin:/n"
for i in [125, 1.3, 2.5, 0, -1, -5.4]:
if mybin(i) != False:
print str(i) + "/t==>/t" + mybin(i) + '/n'

print "测试2-- mydev:/n"
for i in ['-1001.1100', '-1101','111.111','0.1101','1001','0']:
if mydec(i) != False:
print i + "/t==>/t" + str(mydec(i)) + '/n'
#print "测试3:/n"
#for i in [ '123' ]:
#if mybin(i) != False:
#print str(i) + "/t==>/t" + mybin(i) + '/n'
#print "测试4:/n"
#for i in ['123', '101.1.1.0', '112-212', '-.23', '111.', '.10']:
#if mydec(i) != False:
#print i + "/t==>/t" + str(mydec(i)) + '/n'