我希望输出在for循环中显示一次

Question

如果Else语句出错，我希望它显示一次。请看我试过的代码。

lists = ['apple','grape','pineapple','orange']
password = "xyz"
def pass1():
for i in lists:
if i == password:
print("Accepted!", "Password : " + i)
break
else:
print("Password not found! Try again")
pass1()

输出：

Password not found! Try again
Password not found! Try again
Password not found! Try again
Password not found! Try again
Process finished with exit code 0

Answer 1

如果我正确理解你的问题，你可以通过删除else来完成，如果循环结束，但你没有在列表中找到密码，那么它就不存在了。

lists = ['apple','grape','pineapple','orange']
password = "xyz"
def pass1():
for i in lists:
if i == password:
print("Accepted!", "Password : " + i)
return
print("Password not found! Try again")
pass1()

另一种更像蟒蛇的方式

def pass2():
if password in lists:
print(print("Accepted!", "Password : " + lists.index(password)))
else:
print("Password not found! Try again")
pass2()

我不明白你为什么不把密码作为参数传递？

也许可以考虑按照来做

def pass3(password, lists):
if password in lists:
print(print("Accepted!", "Password : " + lists.index(password)))
else:
print("Password not found! Try again")
lists = ['apple','grape','pineapple','orange']
password = "xyz"
pass3(password, lists)

Answer 2

实际上，如果你只想检查列表中的值，就不需要循环，只需尝试一下：

def pass1():
if password in lists:
print("Accepted!", "Password : " + password)
else:    
print("Password not found! Try again")

但如果你仍然想迭代列表，你可以使用这样的返回：

def pass1():
for i in lists:
if i == password:
return print("Accepted!", "Password : " + i)
return print("Password not found! Try again")

因为如果不使用return，即使密码为true，最后一个代码仍然会打印出来。

Answer 3

在for loop上使用else的另一种方法
else block只有在每个项目都用完时才执行：

lists = ['apple','grape','pineapple','orange']
password = "xyz"
def pass1():
for i in lists:
if i == password:
print("Accepted!", "Password : " + i)
break
else:
print("Password not found! Try again")
pass1()