而使用比较运算符

Question

我正在自学Python，有以下问题：

这是我的“清单”：

• 使用while循环获取4个动物的用户输入animal_name
• 在while循环条件中使用计数器num_animals
• 将名称附加到字符串变量all_animals
• 用户可以通过键入“退出”提前退出（检查；如果动物名称为“退出”并中断）
• 循环完成后，打印所有动物的名称
• 如果退出循环后动物名称为空，则打印“无动物”

已编辑 我编写了以下代码，但它不起作用。我需要改变什么，这样动物的每一次输入都会被计数

animal_name = input("Put in 4 animal names in total per time or \"exit\" for break")

num_animals = 0

tot_animals = 4

all_names = ""

while num_animals <= tot_animals:
    print(num_animals, "now")
    num_animals += 1
    all_animals += animal_name + "," # connect the name to all names.

    if animal_name.lower() == ("exit"):
        break

if len(all_animals) == 0: # len is 0, then it's empty
    print("no animals")

print("names of all animals: ", all_animals)

来自@Zhd Zilin的改进代码

Answer 1

num_animals = 0
tot_animals = 4
all_names = ""
while num_animals <= tot_animals: # will execute 5 times, 0,1,2,3,4...
    # move into loop, everytime it run, it will ask you input
    animal_name = input("Put in 4 animal names in total per time or \"exit\" for break\n") 
    print(num_animals, "now")
    num_animals += 1

    # when input is exit, quit the program
    if animal_name.lower() == "exit":
        break

    all_names += animal_name + "," # Move this line under break, if "exit" input, don't add it to names, connect the name to all names.

if len(all_names) == 0: # len is 0, then it's empty
    print("no animals")

print("names of all animals: ", all_names)

更新程序，请参阅while语句行的注释

Answer 2

这应该是可行的

num_animals = 0
tot_animals = 4
all_names = [] # Store the names in a list instead

print("Enter names of 4 animal or type 'exit' to stop.")

while num_animals < tot_animals:
    print("Input an animal name")
    animal_name = input(":")
    if animal_name.lower() == "exit":
        break
    else:
        num_animals += 1
        all_names.append(animal_name) # Use .append() method to element to list

if len(all_names) != 0:
    print("All animals:",tot_animals,all_names)
else:
    print("No animals")

另外，要使您的代码干净，改进安排以便于调试

Answer 3

num_animals = 0
tot_animals = 4
all_names = ""

while num_animals <= tot_animals:
    # Doing this within the while loop will prompt the user for input
    # each iteration of the loop.
    animal_name = input("Put in 4 animal names in total per time or \"exit\" for break")
    if animal_name.lower() == "exit":
        break

    num_animals += 1
    # This will append the user's input to all_names
    all_names += animal_name + " "

if len(all_names) == 0:
    print("no animals")
else:
    print("names of all animals: ", all_names)