TypeError:列表索引必须是整数或切片，而不是浮点数

问题描述

def convBin():
    cont = []
    rest = []
    dev = []
    decimal = []

    print("Ingrese el valor a convertir: ")
    valor = ast.literal_eval(input())

    if isinstance(valor, int):
        while valor > 0:
                z = valor // 2
            resto = valor%2
            valor = valor // 2
            cont.append(z)
            rest.append(resto)

        cont.reverse()
        rest.reverse()

        dev.append(cont[0])

        x = 0
        while x <= (len(rest) - 1):
            dev.append(rest[x])
            x += 1

        print(" ")
        print("Lista de devoluciones: ")
        print(dev)
        print("")

    elif isinstance(valor, float):
        a = valor // 1
        b = valor % 1

        while a > 0:
            z = a // 2
            resto = a%2
            a = a // 2
            cont.append(z)
            rest.append(resto)

        cont.reverse()
        rest.pop()

        dev.append(cont[1])

        for i in rest:
            dev.append(rest[i])

        print("Inserte el número de error minimo")
        num = input()

        while num > 0:
            dec = b * 1
            dec2 = dec//1
            dec %= 1
            decimal.append(dec2)


        print("Parte entera: ")
        print(dev)
        print("Parte decimal:")
        print(num)

    else:
        print("Ha aparecido un error")

Its shows me an error that i can´t append a float into a list.

After asking you a number, it controls which type of number is it. When it is an int, it doesn´t have any problem. But when it´s a float, it says that it can´t add a float into a list where it´s saved the numbers of the operations made before.

Can someone explain it to me why I can´t append floats into a list or how can I solve the problem?

Thanks.

解决方案

for i in rest will give you the actual item in the list, and not index. From your code, it seems that you want to append the value. But actually, you are treating the value as index again, and trying to fetch it from the array.

for i in rest:
            dev.append(rest[i])

Fix:

Just change above to:

dev.extend(rest)

But this code, takes a value from rest, then again uses that value as an index, and if that value i turns out to be a float, it throws an exception.

You haven't mentioned which line gives you this error. But I think it must be this one. It might give many other unexpected errors like array out of bound, etc

This is the error I get, if I run your code for valor = 18.5

https://ideone.com/HGagLb

Difference between the above example, and the one below(from your code, where you handle int):

x = 0
while x <= (len(rest) - 1):
    dev.append(rest[x])
    x += 1

is that, in the first case, i is actually the item(int or float) in the list rest, while in the later one, it's a valid index.

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