python十进制浮点数（小数）转换为二进制

最近学习计算机系统概论，经常需要将十进制的浮点数转换为二进制的形式，加之有相关作业，写个代码与大家分享。逻辑稍有混乱，不过还是很好用的

#传入一个浮点型字符串和有效数字位数
def fraction_to_binary(fraction_string, significant_binary_digits):
    def print_binary(number_string, fraction_length):
        dotleft=""

        netative="+"
        if float(number_string)<0:
            netative="-"
            

        if "." in number_string:
            a,b=number_string.split(".")
        else:
            a=number_string
        a=int(a)
        if a<0:
            a=-a
        result=[]
        def dec2bin(number):
            if number==1:
                result.insert(0,"1")
            elif number==0:
                result.insert(0,"0")
            else:
                if number%2==0:
                    result.insert(0,"0")
                    dec2bin(number//2)
                else:
                    result.insert(0,"1")
                    dec2bin(number//2)
        dec2bin(int(a))
        for i in result:
            dotleft+=i
        #print(dotleft)
        if "." in  number_string:

            number=float("0."+b)
            count=0
            dotright=""
            number=float("0."+b)
            while count<fraction_length:
                if number*2>=1:
                    dotright=dotright+"1"
                    number=number*2-1
                    count+=1
                else:
                    number*=2
                    dotright=dotright+"0"
                    count+=1
        else:
            dotright="0"*fraction_length
        temp=netative+dotleft+"."+dotright
        return temp[1:]
    
    answer=print_binary(fraction_string, 15)
    first_1=answer.index("1")
    liebiao=list(answer[answer.index(".")+1:first_1+significant_binary_digits+1])
    #print(liebiao)
    #打印列表
    for i in liebiao:
        print(i,end=" ")
    print()
    #列表打印完毕

    #处理进位
    woshigetemp=-1
    liebiao.insert(0,"0")
    if liebiao[-1]=="1":

        while 12138:
                if liebiao[woshigetemp]=="0":
                
                
                    liebiao[woshigetemp]="1"
                    break
                elif liebiao[woshigetemp]==".":
                    pass
                
                else:
                    liebiao[woshigetemp]="0"
                
                woshigetemp-=1
    #print(liebiao[:-1])
    ###

    ###打印
    print_str=""
    #liebiao=liebiao[:-1]
    liebiao=liebiao[:liebiao.index("1")+significant_binary_digits]
    #print(liebiao)
    liebiao.insert(1,".")
    for i in liebiao:
        print_str+=i
    
    print(print_str)