是否有办法从用户输入中读取单个字符?例如,他们在终端上按下一个键,它就会返回(有点像getch())。我知道Windows中有这个功能,但我想要跨平台的东西。
当前回答
python中的curses包可以使用一些语句从终端进入“原始”模式进行字符输入。Curses的主要用途是接管屏幕进行输出,这可能不是你想要的。此代码片段使用print()语句代替,这是可用的,但必须注意curses如何更改附加到输出的行结束符。
#!/usr/bin/python3
# Demo of single char terminal input in raw mode with the curses package.
import sys, curses
def run_one_char(dummy):
'Run until a carriage return is entered'
char = ' '
print('Welcome to curses', flush=True)
while ord(char) != 13:
char = one_char()
def one_char():
'Read one character from the keyboard'
print('\r? ', flush= True, end = '')
## A blocking single char read in raw mode.
char = sys.stdin.read(1)
print('You entered %s\r' % char)
return char
## Must init curses before calling any functions
curses.initscr()
## To make sure the terminal returns to its initial settings,
## and to set raw mode and guarantee cleanup on exit.
curses.wrapper(run_one_char)
print('Curses be gone!')
其他回答
内置的raw_input应该会有所帮助。
for i in range(3):
print ("So much work to do!")
k = raw_input("Press any key to continue...")
print ("Ok, back to work.")
我对python3的解决方案,不依赖于任何pip包。
# precondition: import tty, sys
def query_yes_no(question, default=True):
"""
Ask the user a yes/no question.
Returns immediately upon reading one-char answer.
Accepts multiple language characters for yes/no.
"""
if not sys.stdin.isatty():
return default
if default:
prompt = "[Y/n]?"
other_answers = "n"
else:
prompt = "[y/N]?"
other_answers = "yjosiá"
print(question,prompt,flush= True,end=" ")
oldttysettings = tty.tcgetattr(sys.stdin.fileno())
try:
tty.setraw(sys.stdin.fileno())
return not sys.stdin.read(1).lower() in other_answers
except:
return default
finally:
tty.tcsetattr(sys.stdin.fileno(), tty.TCSADRAIN , oldttysettings)
sys.stdout.write("\r\n")
tty.tcdrain(sys.stdin.fileno())
(目前)排名第一的答案(带有ActiveState代码)过于复杂。当仅仅一个函数就足够了时,我不认为有理由使用类。下面是两个实现,它们实现了相同的功能,但代码可读性更强。
这两个实现:
可以在python2或python3中正常工作 可以在Windows, OSX和Linux上工作 只读取一个字节(即,它们不等待换行符) 不要依赖任何外部库 是自包含的(没有函数定义之外的代码)
版本1:易读且简单
def getChar():
try:
# for Windows-based systems
import msvcrt # If successful, we are on Windows
return msvcrt.getch()
except ImportError:
# for POSIX-based systems (with termios & tty support)
import tty, sys, termios # raises ImportError if unsupported
fd = sys.stdin.fileno()
oldSettings = termios.tcgetattr(fd)
try:
tty.setcbreak(fd)
answer = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, oldSettings)
return answer
版本2:避免重复导入和异常处理:
[编辑]我错过了ActiveState代码的一个优点。如果您计划多次读取字符,该代码可以避免在类unix系统上重复Windows导入和ImportError异常处理的成本(可以忽略不计)。虽然你可能应该更关心代码的可读性,而不是可以忽略的优化,这里有一个替代方案(它类似于Louis的答案,但getChar()是自包含的),它的功能与ActiveState代码相同,更可读:
def getChar():
# figure out which function to use once, and store it in _func
if "_func" not in getChar.__dict__:
try:
# for Windows-based systems
import msvcrt # If successful, we are on Windows
getChar._func=msvcrt.getch
except ImportError:
# for POSIX-based systems (with termios & tty support)
import tty, sys, termios # raises ImportError if unsupported
def _ttyRead():
fd = sys.stdin.fileno()
oldSettings = termios.tcgetattr(fd)
try:
tty.setcbreak(fd)
answer = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, oldSettings)
return answer
getChar._func=_ttyRead
return getChar._func()
使用上述getChar()版本的示例代码:
from __future__ import print_function # put at top of file if using Python 2
# Example of a prompt for one character of input
promptStr = "Please give me a character:"
responseStr = "Thank you for giving me a '{}'."
print(promptStr, end="\n> ")
answer = getChar()
print("\n")
print(responseStr.format(answer))
两个答案中逐字引用的ActiveState配方是过度设计的。它可以归结为:
def _find_getch():
try:
import termios
except ImportError:
# Non-POSIX. Return msvcrt's (Windows') getch.
import msvcrt
return msvcrt.getch
# POSIX system. Create and return a getch that manipulates the tty.
import sys, tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
return _getch
getch = _find_getch()
这可能是上下文管理器的一个用例。不考虑Windows操作系统,以下是我的建议:
#!/usr/bin/env python3
# file: 'readchar.py'
"""
Implementation of a way to get a single character of input
without waiting for the user to hit <Enter>.
(OS is Linux, Ubuntu 14.04)
"""
import tty, sys, termios
class ReadChar():
def __enter__(self):
self.fd = sys.stdin.fileno()
self.old_settings = termios.tcgetattr(self.fd)
tty.setraw(sys.stdin.fileno())
return sys.stdin.read(1)
def __exit__(self, type, value, traceback):
termios.tcsetattr(self.fd, termios.TCSADRAIN, self.old_settings)
def test():
while True:
with ReadChar() as rc:
char = rc
if ord(char) <= 32:
print("You entered character with ordinal {}."\
.format(ord(char)))
else:
print("You entered character '{}'."\
.format(char))
if char in "^C^D":
sys.exit()
if __name__ == "__main__":
test()
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