st-scripts: comparison input_output/script.rst.orig

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+.. Objectives
+.. ----------
+.. #. How to print some value
+.. #. How to print using modifiers
+.. #. How to take input from user
+.. #. How to display a prompt to the user before taking the input
+.. Prerequisites
+.. -------------
+..   1. Loops
+.. Author              : Nishanth Amuluru
+Internal Reviewer   : Puneeth
+External Reviewer   :
+Checklist OK?       : <put date stamp here, if OK> [2010-10-05]
+Script
+------
+Hello friends and welcome to this tutorial on Input/Output
+{{{ Show the slide containing title }}}
+{{{ Show the slide containing the outline slide }}}
+Input and Output are used in almost every program we use.
+In this tutorial, we shall learn how to
+* Output data
+* Take input from the user
+type
+::
+a = "This is a string"
+a
+print a
+<<<<<<< local
+print a, prints the value of a.
+=======
+``print a``, obviously, is printing the value of ``a``.
+>>>>>>> other
+As you can see, even when you type just a, the value of a is shown.
+But there is a difference.
+.. #[Amit: The next sentence does seem to be clear enough]
+Typing a shows the value of a while print a prints the string. This difference
+becomes more evident when we use strings with newlines in them.
+type
+::
+b = "A line \n New line"
+b
+print b
+As you can see, just typing b shows that b contains a newline character.
+While typing print b prints the string and hence the newline.
+Moreover when we type just a, the value a is shown only in interactive mode and
+does not have any effect on the program while running it as a script.
+.. #[punch: I think we could show that?]
+We shall look at different ways of outputting the data.
+<<<<<<< local
+.. #[Amit: C's printf syntax ?? i think its better to elaborate the
+idea]
+print statement  in python supports string formatting.
+Various arguments can be passed to print using modifiers.
+=======
+``print`` statement also accepts the syntax of C's ``printf`` statement.
+Various arguments can be passed to ``print`` using modifiers.
+>>>>>>> other
+type
+::
+x = 1.5
+y = 2
+z = "zed"
+print "x is %2.1f y is %d z is %s"%(x,y)
+As you can see, the values of x and y are substituted in place of
+``%2.1f`` and ``%d``
+{{{ Pause here and try out the following exercises }}}
+%% 1 %% What happens when you do ``print "x is %d y is %f" %(x, y)``
+{{{ continue from paused state }}}
+We see that the ``int`` value of x and ``float`` value of y are
+printed corresponding to the modifiers used in the print statement.
+We can also see that ``print`` statement prints a new line character
+at the end of the line, everytime it is called. This can be suppressed
+by using a "," at the end ``print`` statement.
+Let us see this by typing out following code on an editor as print_example.py
+{{{ open an editor }}}
+type
+::
+print "Hello"
+print "World"
+print "Hello",
+print "World"
+Now we run the script using %run /home/fossee/print_example.py
+As we can see, the print statement when used with comma in the end, prints a
+space instead of a new line.
+Now we shall look at taking input from the user.
+We will use the ~~raw_input~~ for this.
+type
+::
+ip = raw_input()
+The cursor is blinking indicating that it is waiting for input
+type
+::
+an input
+and hit enter.
+Now let us see what is the value of ip by typing.
+::
+ip
+We can see that it contains the string "an input"
+{{{ Pause here and try out the following exercises }}}
+%% 2 %% enter the number 5.6 as input and store it in a variable called c.
+{{{ continue from paused state }}}
+We have to use the raw_input command with variable c.
+type
+::
+c = raw_input()
+5.6
+c
+Now let us see the type of c.
+::
+type(c)
+We see that c is a string. This implies that anything you enter as input, will
+be taken as a string no matter what you enter.
+{{{ Pause here and try out the following exercises }}}
+%% 3 %% What happens when you do not enter anything and hit enter
+{{{ continue from paused state }}}
+::
+d = raw_input()
+<RET>
+d
+We see that when nothing is entered, an empty string is considered as input.
+raw_input also can display a prompt to assist the user.
+::
+name = raw_input("Please enter your name: ")
+prints the string given as argument and then waits for the user input.
+{{{ Pause here and try out the following exercises }}}
+%% 4 %% How do you display a prompt and let the user enter input in next line
+{{{ continue from paused state }}}
+.. #[Puneeth: We didn't talk of new-line character till now, did we?]
+.. #[Puneeth: non-programmers might not know?]
+.. #[Amit: Well there is a discussion earlier about new lines, I think its good
+.. as a slight trick question. But may be next line is a more easier lexicon]
+The trick is to include a newline character at the end of the prompt string.
+::
+ip = raw_input("Please enter a number in the next line\n> ")
+prints the newline character and hence the user enters input in the next line
+{{{ Show summary slide }}}
+This brings us to the end of the tutorial.
+In this totorial we have learnt
+* How to print some value
+* How to print using modifiers
+* How to take input from user
+* How to display a prompt to the user before taking the input
+{{{ Show the "sponsored by FOSSEE" slide }}}
+This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
+Hope you have enjoyed and found it useful.
+Thank You.