Hướng dẫn does python3 support raw_input?

As others have indicated, the raw_input function has been renamed to input in Python 3.0, and you really would be better served by a more up-to-date book, but I want to point out that there are better ways to see the output of your script.

From your description, I think you're using Windows, you've saved a .py file and then you're double-clicking on it to run it. The terminal window that pops up closes as soon as your program ends, so you can't see what the result of your program was. To solve this, your book recommends adding a raw_input / input statement to wait until the user presses enter. However, as you've seen, if something goes wrong, such as an error in your program, that statement won't be executed and the window will close without you being able to see what went wrong. You might find it easier to use a command-prompt or IDLE.

Use a command-prompt

When you're looking at the folder window that contains your Python program, hold down shift and right-click anywhere in the white background area of the window. The menu that pops up should contain an entry "Open command window here". [I think this works on Windows Vista and Windows 7.] This will open a command-prompt window that looks something like this:

    Microsoft Windows [Version 6.1.7601]
    Copyright [c] 2009 Microsoft Corporation.  All rights reserved.

    C:\Users\Weeble\My Python Program>_

To run your program, type the following [substituting your script name]:

    python myscript.py

...and press enter. [If you get an error that "python" is not a recognized command, see //showmedo.com/videotutorials/video?name=960000&fromSeriesID=96 ] When your program finishes running, whether it completes successfully or not, the window will remain open and the command-prompt will appear again for you to type another command. If you want to run your program again, you can press the up arrow to recall the previous command you entered and press enter to run it again, rather than having to type out the file name every time.

Use IDLE

IDLE is a simple program editor that comes installed with Python. Among other features it can run your programs in a window. Right-click on your .py file and choose "Edit in IDLE". When your program appears in the editor, press F5 or choose "Run module" from the "Run" menu. Your program will run in a window that stays open after your program ends, and in which you can enter Python commands to run immediately.

    In Python 2

    >>> age = input['How old are you ?']
    How old are you ?: 30 # entered data is treated as number.
    >>> print age
    30

    >>> age = input['How old are you ? :']
    How old are you ? : '30' # entered data is treated as string.
    >>> print age
    '30'

   In Python 2

   >>> age = raw_input["How old are you ? :"]
   How old are you ? : 30 # entered data is treated as string even without ''
   >>> print age
   '30'

    >>> age = raw_input["How old are you ? :"]
    How old are you ? : '30' # entered data treated as string including ''
    >>> print age
    "'30'"

    In Python 3

    >>> age = input["How old are you ? :"]
    How old are you ? : 30
    >>> print[age]
    '30'

    >>> age = input["How old are you ? :"]
    How old are you ? : '30' # entered data treated as string with or without ''
    >>> print[age]
    "'30'"

    >>> age = raw_input["How old are you ? :"] # will result NameError
    Traceback [most recent call last]:
    File "", line 1, in 
    NameError: name 'raw_input' is not defined

    In Python 2

    >>> age = int[raw_input["How old are you ? :"]]
    How old are you ? : 30
    >>> print[age]
    30

    >>> age = int[raw_input["How old are you ? :"]]
    How old are you ? : '30'
    >>> print[age]
    Traceback [most recent call last]:
    File "", line 1, in 
    ValueError: invalid literal for int[] with base 30: "'30'"

    In Python 3

    >>> age = int[input["How old are you ? :"]]
    How old are you ? : 30
    >>> print[age]
    30

    >>> age = int[input["How old are you ? :"]]
    How old are you ? : '30'
    >>> print[age]
    Traceback [most recent call last]:
    File "", line 1, in 
    ValueError: invalid literal for int[] with base 30: "'30'"

In Python 2

#!/usr/bin/python
import math
radius = int[raw_input["Please enter the radius of the circle : "]]
area_of_circle = math.pi * radius**2
print area_of_circle

[email protected]:~$ sudo nano circle_area2.py

[email protected]:~$ sudo python circle_area2.py

    In Python 3

    #!/usr/bin/python3
    import math
    radius = int[input["Please enter the radius of the circle : "]]
    area_of_circle = math.pi * radius**2
    print[area_of_circle]

[email protected]:~$ sudo nano circle_area3.py

[email protected]:~$ sudo python circle_area3.py