How can the end of "for" be a user-defined variable?

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How can the end of "for" be a user-defined variable?

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In a for in C, we define "start, end and increment step. " I know Python is not like this. I saw it called foreach . I wish the end of my for to be defined by the user. And that, at each iteration until the end of for, a value was requested from the user and saved in a vector.

I tried:

num_tracos = raw_input()

tracos_treino = np.arange(100)

for i in num_tracos:
    print "Digite o traco", i+1, " para o treinamento"
    tracos_treino[i] = raw_input()

I also tried a while , but it did not work because I never ends (it actually gives error when it reaches entry 101, because it no longer fits into the vector, but if it were not for that, it would be infinite):

num_tracos = raw_input()

 tracos_treino = np.arange(100)

i=0
while i < num_tracos :
    print "Digite o traco", i+1, " para o treinamento"
    tracos_treino[i] = raw_input()
    i = i+1

I've always heard that for that a while , unless you go iterate (ie never) . I read this in "Learn Python The Hard Way."

Anyway, neither is working the way I would.

python for

asked by anonymous 12.05.2018 / 11:39

2 answers

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To be able to implement what you have in mind you have to do the following:

create a condition to end the cycle while , in the definition of it
create input on the console to read an input variable
From there, map the input variable to the condition that closes cycle while loop

This definition might be something of the sort (pseudo-code structure):

continue while input variable is different from 0

There, at the end of each iteration cycle you should put the following:

want to continue (yes - 1, no - 0) - print to the console
You should then read the input for a variable that should be the same as that found in the cycle header when it says it continues if it is not 0

12.05.2018 / 13:23

Identify which page requests another through require_once Moving files in folders

score 2 · Accepted Answer

What version of Python are you using? I'll give my idea on top of Python 3. In fact the in Python is a bit different than in C, but you can do these tasks without problems, just understand the structure.

Let's say you want to make a for to count from 0 to 9, in C you would do this as follows:

    for(int c=0; c<10; c++) {
        printf("%d\n", c);
    }

In Python this would look a bit different, see below:

    for c in range(0, 10):
        print(c)

Notice that in Python, I use a range of values to go through, in this case from 0 to 9, these values can be overridden by variables. You can also set the iteration step.

    for c in range(0, 10, 2):
        print(c)

Notice the third parameter of the range, it makes the count happen by 2 in 2. Leading to your question ... In Python we have something that in my opinion helps a lot, it's the lists.

    # Definimos uma lista para guardar os valores.
    tracos_treino = []
    # Podemos solicitar ao usuário quantos ítens ele quer inserir na lista.
    tamanho = int(input('Informe a quantidade de ítens desejados:'))
    # Fazemos a iteração.
    # Aqui utilizo a variável 'tamanho' para determinar o fim da contagem.
    for c in range(0, tamanho):
        valor = input('Digite o traco ' + str(c+1) + ' para o treinamento:')
        tracos_treino.append(valor)   # Adiciona ao final da lista.
    # Depois podemos fazer a exibição desses valores.
    for c in range(0, tamanho):
        print(tracos_treino[c])

I hope I have helped with something: D