Print vs return, Python Programming

Print vs Return

Here are two different method declarations:

def f1(x):

print x + 1 def f2(x):

return x + 1

What happens when  we call them?

>>> f1(3)

4

>>> f2(3)

4

 

It looks like they behave in exactly the similar way.  But they don't, exactly.  Look at this example:

 

>>> print(f1(3))

4

None

>>> print(f2(3))

4

 

In the case of f1, the function, when  calculated, prints 4; then  it gives the value  None, which  is given by the Python file. In the case of f2, it does not give  anything, but it gives 4, which  is printed by the Python core. Finally, we may look the difference here:

 

>>> f1(3) + 1

4

Traceback (most recent call last):

File "", line 1, in ?

TypeError: unsupported operator type(s) for +: 'NoneType' and 'int'

>>> f2(3) + 1

5

 

In the ?rst case, the function does not give a value,  so there  is nothing to include  to 1, and an error is created. In the second  type, the function gives the value  4, which  is included to 1, and  the result,  5, is output by the Python read-eval-print loop.

Print  is very needful  for debugging. It is very important to know  that you may print  out as many  values as you want  in one line:

 

>>> x = 100

>>> print 'x', x, 'x squared', x*x, 'xiv', 14

x 100 x squared 10000 xiv 14

 

We have also snuck in another data type on you: strings. A string  is a sequence of words. You can build a string  using  single or double quotes;  and access individual elements of strings using indexing.

 

>>> s1 = 'hello world'

>>> s2 = "hello world"

>>> s1 == s2

True

>>> s1[3]

'l'

 

As you  may  see,  indexing indicates  to the  extraction of a particular element of a string,  by using square brackets [i] where i is a number that  identi?es the  location  of the  character that  you wish to extract (note that the indexing starts  with 0 ).

 

Posted Date: 8/9/2012 7:01:08 AM | Location : United States







Related Discussions:- Print vs return, Assignment Help, Ask Question on Print vs return, Get Answer, Expert's Help, Print vs return Discussions

Write discussion on Print vs return
Your posts are moderated
Related Questions
Define a function that draws a pentagon of a size you provide when you call the function. Include a ''''''docstring'''''' as the first line of the function''s body — it tells the p

1)    Write a python programmecomparing for and while loops like the following. Math Times table For Loop: 2x1=2 2x2=4 ..... 2x12=24 While Loop: 3x1=3 3x

Synthetic models One  goal  of various  people in a variety of sub-disciplines of  electrical  engineering and  computer science is automatic synthesis of machine from  formal

Your assignment for the semester will involve the development of a system for drawing trees using the Python programming language and the turtle graphics module (turtle.py). Comple

List mutation and shared structure Lists are mutable data  structures, which defines  that  we can actually modifies  the values  stored in their components. We do this by usi

For this assignment, you are to: 1.    Modify the output format of your Python script from Assignment 1 to match the input format of your C program from Assignment 2. 2.    W

Suppose the cover price of a book is $24.95, but bookstores get a 40% discount. Shipping costs $3 for the first copy and 75 cents for each additional copy. What is the tota

Python programs Every  general-purpose computer has a various detailed design, which  defines  that  the way  its program requires  to be specified is different. The "machine

Write a program that asks the user to enter a number of seconds. The responses of the program will vary depending on the length of seconds: • If the number of seconds is under 60

Python Programs You must submit the source code and samples of output for each program.Please do not provide python file (eg. Filename.py). Copy all source code to one word fi