在python中扫描用户输入
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scanning user input in python
提问by user2232076
direction = input("enter a direction: ")
if direction != "quit" and direction != "go north" and direction != "go south" and direction != "go east" and direction != "go west" and direction != "go up" and direction != "go down" and direction != "look":
print ("please enter in the following format, go (north,east,south,west,up,down)")
elif direction == "quit":
print ("OK ... but a small part of you may never leave until you have personally saved Muirfieland from the clutches of evil .. Bwahahahahahah (sinister laugh) ... the game should then end.")
elif direction == "look":
print ("You see nothing but endless void stretching off in all directions ...")
else:
print ("You wander of in the direction of " + direction)
i need to know how to do this in python. i need to scan user inputs first 2 letters for example
我需要知道如何在 python 中做到这一点。例如，我需要扫描用户输入的前 2 个字母
i = user_input
#user inputs go ayisgfdygasdf
i need it to be able to scan the user input, check if the first 2 letters are go, and if they are go but it doesnt recognise the second word which in this case is "ayisgfdygasdf" then to print "sorry, i cant do that"
我需要它能够扫描用户输入，检查前两个字母是否消失，如果它们消失，但它无法识别第二个单词，在这种情况下是“ayisgfdygasdf”然后打印“对不起，我不能做那”
回答by e.beyer
You can access characters of a string in python by index using the [] notation. You can check the first two character in a string by typing user_input[:2]. This code will include all characters up to, but not including the index typed. So this notation will include user_input[0] and user_input[1]. You can then check if user_input[:2] is equal to 'go' or not, and continue from there.
您可以使用 [] 表示法通过索引访问 python 中字符串的字符。您可以通过键入 user_input[:2] 来检查字符串中的前两个字符。此代码将包括所有字符，但不包括键入的索引。所以这个符号将包括 user_input[0] 和 user_input[1]。然后，您可以检查 user_input[:2] 是否等于 'go'，然后从那里继续。
Hope this helped.
希望这有帮助。
回答by Juan Carlos Moreno
Instead try using:
而是尝试使用：
direction = sys.stdin.readlines()
It may require you to ctrl+D after you are done but you will be able to capture so much more.
完成后可能需要您按 ctrl+D，但您将能够捕获更多内容。
Also, to get the subarray you can then you can even check:
此外，要获得子数组，您甚至可以检查：
direction[:2] != "go"
or alternatively, for more readable code:
或者，对于更具可读性的代码：
if not direction.startswith("go"):
Also I'd recommend, for making your code more readable,
我还建议，为了使您的代码更具可读性，
defined_direction = frozenset(["quit", "go north", "go south"])
if( direction not in defined_direction):
print "please enter...."
回答by Disconnect3d
He could also try using:
他也可以尝试使用：
directions.split()
But it may require to use try/except in some cases.
但在某些情况下可能需要使用 try/except 。
For more information about split and methods try using:
有关拆分和方法的更多信息，请尝试使用：
dir(directions)
to see what methods object directions have
查看对象方向有哪些方法
or:
或者：
help(directions.split)
to see help about a specific method (in this case method split of object directions)
查看有关特定方法的帮助（在本例中为对象方向的方法拆分）
回答by dckrooney
You can index the individual characters of your input:
您可以索引输入的单个字符：
if direction[:2] == "go":
print "Sorry, I can't do that."
However, trying assign an if-else branch to each possible input is typically a bad choice... It becomes difficult to maintain very quickly.
然而，尝试为每个可能的输入分配一个 if-else 分支通常是一个糟糕的选择......它变得很难快速维护。
A cleaner approach in this case might be to define a dictionary with valid input as follows:
在这种情况下，一种更简洁的方法可能是定义一个具有有效输入的字典，如下所示：
input_response = {"quit":"OK ... but", "go north": "You wander off north", \
"go south": "You wander off south"} # etc
You could then re-write your code to something like:
然后，您可以将代码重新编写为：
try:
print input_response[direction]
except KeyError:
if direction[:2] == "go":
print "Sorry, I can't do that."
else:
print ("please enter in the following format...")
