python学习实例（2）

      #===================================
      #2.2 不同进制间的转换
      #===================================
      #+++++++++++++++++++++++++++++++++++
      #2.2.1. 二进制数转换为十进制数
      #+++++++++++++++++++++++++++++++++++
      #<程序：2-to-10进制转换>
      b=input("Please enter a binary number:")
      d=0;
      for i in range(0,len(b)):
      if b[i] == '1':
       weight = 2**(len(b)-i-1)
       d = d+weight;
      print(d)
      #<程序：改进后的2-to-10进制转换>
      b=input("Please enter a binary number:")
      d=0; weight=2**(len(b)-1);
      for i in range(0,len(b)):
      if b[i] == '1':
       d = d+weight;
       weight=weight//2; #‘//’是整数除法
      print(d)
      #+++++++++++++++++++++++++++++++++++
      #2.2.2. 十进制数转换为二进制数
      #+++++++++++++++++++++++++++++++++++
      #<程序：整数的10-to-2进制转换>
      x= int(input("Please enter a decimal number:"))
      r = 0;
      Rs = [];
      while(x != 0):
       r = x% 2
       x = x//2
       Rs = [r]+Rs
      for i in range(0,len(Rs)):
      #从最高位到最低位依次输出；Rs[0]存的是最高位， Rs[len(Rs)-1]存的是最低位。
       print(Rs[i],end='')
      #<程序：整数的10-to-2进制转换-递归>
      def convert(x):		 #把10进制数x转换为2进制数，并返回结果列表。
      if x<2: return([x]) #x=0 或 1，所以返回x
       r= x%2; #r 是2除x的余数
      return(convert(x//2)+[r])   # 结果=[x//2的二进制，r]
      num = int(input("Please enter a decimal number:"))
      Rs= convert(num)
      for i in range(0, len(Rs)):
      print (Rs[i],end='')
      #=====================================================================================
      #===================================
      #2.4. 一切都是逻辑（Logic）
      #===================================
      #+++++++++++++++++++++++++++++++++++
      #2.4.3. 用逻辑做加法
      #+++++++++++++++++++++++++++++++++++
      #<程序: 全加器>
      def FA(a,b,c):  # Full adder
       Carry = (a and b) or (b and c) or (a and c)
       Sum = (a and b and c) or (a and (not b) and (not c)) \
      or ((not a) and b and (not c)) or ((not a) and (not b) and c)
      return Carry, Sum
      #<程序：完整的加法器 Carry Ripple adder>
      def add(x,y): # x, y are lists of True or False, c is True or False
      # return carry and a list of x+y
      while len(x) < len(y): x = [False]+x #前面补0
      while len(y) < len(x): y = [False]+y	#前面补0
       L=[];Carry=False
      for i in range(len(x)-1,-1,-1):  #从最后一位一个个往前加
       Carry,Sum=FA(x[i],y[i],Carry)
       L=L+[Sum]
      return (Carry, L)
      #<程序：乘法器>
      def multiplier(x,y): # 求x*y
       S=[];
      for i in range(len(y)-1,-1,-1):
      if y[i] == True: #y[i]是 1，要将x加进到S
       C, S=add(S,x)
      if C==True: S=[C]+S
       x=x+[False]			#每一次x都要向左移一位，后面补0
      return(S)
  
 

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原文链接：fantianzuo.blog.csdn.net/article/details/83025184