python-2.7 - Python “expected an indented block”

Question

我正在运行以下脚本进行验证:

def num_val(x):
while True:
    try:
        userInput = raw_input("Please, enter the length of list " + x + " (only values from 1 to 100 are valid): ")
        val = int(userInput)
    except ValueError:
        print("Entered value must be a number. Please, write the number again")
        continue
    if userInput < 1 or userInput > 100:
        print ("Entered value must be a number in range from 1 to 100. Please write the number again")
    else:
break
num_val("a")

我收到以下消息:

print ("Entered value must be a number in range from 1 to 100. Please write the number again")
    ^
IndentationError: expected an indented block

你能告诉我那条线是什么问题吗？

Answer 1

通过复制和粘贴，您的代码看起来可能包含空格和制表符，这可能会导致奇怪的错误。以下对我有用:

def num_val(x):
    while True:
        try:
            userInput = raw_input("Please, enter the length of list " + x + " (only values from 1 to 100 are valid): ")
            val = int(userInput)
        except ValueError:
            print("Entered value must be a number. Please, write the number again")
            continue
        if val < 1 or val > 100:    # <-- use "val" instead of "userInput"
            print ("Entered value must be a number in range from 1 to 100. Please write the number again")
        else:
            break

num_val("a")

如何预防这类问题？取决于您的编辑器。许多编辑器都有“扩展选项卡”或类似的设置，对于Python代码，您应该利用该功能。这样，当您按下Tab键时，编辑器将插入空格。在Python中，Tab characters line up every 8 columns和其他缩进处的空格可能会使解析器感到困惑。

另请注意，if语句应使用val而不是userInput，因为val是数字，而userInput是文本。