十进制小数分数与二进制的转换 |
您所在的位置:网站首页 › 数学分数转小数怎么转的 › 十进制小数分数与二进制的转换 |
十进制分数转换为二进制数 使用短除法。 例如将十进制分数11/28转换为二进制数,过程如下: 1、首先将分子分母分别转换成二进制 (11)10=(1011)2 (28)10=(11100)2 2、使用短除,借位时是借2,商只能是0或1 二进制小数转换为十进制小数 使用按权展开求和法,小数点左边是2的正数次方,从0开始;小数点右边是2的负数次方,从-1开始。 例如将101.111(2)转换成十进制数 1*(2^2)+0*(2^1)+1*(2^0) # 整数部分 + 1*(2^(-1))+1*(2^(-2))+1*(2^(-3)) # 小数部分 =5.875 附 python 版十进制与二进制转换 # coding=UTF-8 from decimal import Decimal def dec2bin(n, bit=20): """ n, integer or float to convert bit, bits after point return binary, string """ negative = False if n < 0: negative = True n *= -1 integer = int(n) decimal = n - integer binary = "" if n == 0: return "0" while integer != 0: result = int(integer % 2) integer /= 2 binary = str(result) + binary if decimal != 0: i = 0 decimal_bin = "" # binary decimal after convert while decimal != 0 and i < bit: result = int(decimal * 2) decimal = decimal * 2 - result decimal_bin += str(result) i += 1 binary = binary + '.' + decimal_bin if negative: binary = '-' + binary return binary def bin2dec(n): """ n binary, support point return integer or float """ negative = False if n < 0: negative = True n *= -1 integer = int(n) decimal = n - integer if integer != 0: integer_str = str(integer) length = len(integer_str) integer = 0 for i in xrange(0, length): bit = int(integer_str[i]) if bit == 1: integer += 2 ** (length - i - 1) elif bit != 0: print "invalid integer:" + str(n) if decimal != 0: decimal_str = str(decimal)[2:] # skip "0." length = len(decimal_str) decimal = 0 for i in xrange(0, length): bit = int(decimal_str[i]) if bit == 1: decimal += 2 ** (-1 * (i + 1)) elif bit != 0: print "invalid decimal:" + str(n) result = integer + decimal if negative: result *= -1 return result def testcases(): for pair in [(125, '1111101'), (1.3, '1.01001100110011001100'), (2.5, '10.1'), (0, '0'), (-1, '-1'), (0.5, '.1')]: assert pair[1] == dec2bin(pair[0]) for pair in [(-1001.1100, -9.75), (-1101, -13), (111.111, 7.875), (0.1101, 0.8125), (1001, 9), (0, 0), (0.1, 0.5)]: assert pair[1] == bin2dec(pair[0]) print "all test case success" if __name__ == "__main__": # testcases() print bin2dec(0.5)
参考:
http://blog.csdn.net/caoguo_app_android/article/details/9955743
|
今日新闻 |
推荐新闻 |
CopyRight 2018-2019 办公设备维修网 版权所有 豫ICP备15022753号-3 |