python - 如何在 Python 中检查没有输入

Question

# Imports
import re

# Variables
contestants = []


def run(string):
    incorrectSymbols = re.compile('[@_!#$%^&*()<>?/\|}{~:]')
    if (incorrectSymbols.search(string) == None):
        return "yes"
    else:
        return "no"


def bootUp():
    print(""">>> Hello judges!
>>> Today you will be viewing 6 contestants!
>>> To continue please enter all contestants names!""")
    contestantNames()


def contestantNames():
    for i in range(0, 6):
        while True:
            x = input(">>> Contestant number " + str(i) + " name: ")
            if run(x) == "yes":
                break
            elif run(x) == "no":
                print(">>> No symbols allowed!")
            elif x=="":            # Here is what im confused about.
                print(">>> You can't leave it blank!")
            else:
                print(">>> Error in run function.")
    contestants.append(x)
    print(contestants)


bootUp()

阅读完这个问题后，我发现多个帐户都说只需使用 (variable)=""即可。但是，这对我不起作用，还有其他想法吗？

我的代码是对一个舞蹈项目的尝试，在该项目中，参赛者轮流参赛，每位评委为每位参赛者打分。简单地说就是一场比赛。这部分代码将是我获取参赛者姓名的开始，我需要确保他们没有符号或留空。

Answer 1

• 不知何故，您的运行 似乎没有按预期工作。它返回"is"和“否”，而不是真假。您的 if else 排序有误，您需要解决这个问题。
• 只需向上移动 if x=='' 条件即可。

# Imports
import re

# Variables
contestants = []


def run(string):
    incorrectSymbols = re.compile('[@_!#$%^&*()<>?/\|}{~:]')
    if (incorrectSymbols.search(string) == None):
        return "yes"
    else:
        return "no"


def bootUp():
    print(""">>> Hello judges!
>>> Today you will be viewing 6 contestants!
>>> To continue please enter all contestants names!""")
    contestantNames()


def contestantNames():
    for i in range(0, 6):
        while True:
            x = input(">>> Contestant number " + str(i) + " name: ")
            if x == "":            # Here is what im confused about.
                print(">>> You can't leave it blank!")
            elif run(x) == "yes":
                break
            elif run(x) == "no":
                print(">>> No symbols allowed!")
            else:
                print(">>> Error in run function.")
    contestants.append(x)
    print(contestants)


bootUp()

• 另一种解决方案是像这样更改运行函数。

def run(string):
    if string == "":
        return
    incorrectSymbols = re.compile('[@_!#$%^&*()<>?/\|}{~:]')
    if (incorrectSymbols.search(string) == None):
        return "yes"
    else:
        return "no"

这将与您的默认值一起使用。