Conditionals- booleans, Python Programming

 

Booleans

 

Before we talk about  conditionals, we require  to clarify the Boolean  data  type.  It has two values False and True. Typical statement that have Boolean values  are numerical comparisons:

 

>>> 7 > 8

False

>>> -6 <= 9

True

 

We can also test  whether data  items  are equal  to each other.  Usually we use  == to test  for equality. It gives True if the two  objects have  same  values.   Sometimes, however, we will be study in knowing whether the two items are the exact same object. In that case we use is:

 

>>> [1, 2] == [1, 2]

True

>>> [1, 2] is [1, 2]

False

>>> a = [1, 2]

>>> b = [1, 2]

>>> c = a

>>> a == b

True

>>> a is b

False

>>> a == c

True

>>> a is c

True

 

Thus, in the examples above, we see that == testing  can be applied to nested loops, and basically gives true  if every one of the individual elements is the similar.  However, is testing,  especially when  applied to nested loops, is more defined, and only returns True if the two objects point to exactly the same instance in memory.

In addition, we can combine Boolean values  conveniently using  and, not, and or:

 

>>> 7 > 8 or 8 > 7

True

>>> not 7 > 8

True

>>> 7 == 7 and 8 > 7

True

 

If

 

Basic conditional instructions have the form:5

if :

else:

 

 

When  the  interpreter encounters a  conditional statement, it  starts  by  evaluating  ,   getting either   True or  False as  a  result.6   If  the given result   is  True,  then   it  will  eval­ uate  ,...,;  if it is not true,  then  it will evaluate ,...,. Crucially, it always calculates only one set of the statements.

 

Now, for example, we can create a functionthat returns the absolute value of its argument.

 

def abs(x):

if x >= 0:

return x

else:

return -x

 

 

We could also have written

def abs(x):

if x >= 0:

result = x

else:

result = -x

return result

 

Python uses the level of indentation of the instructions to decide  which  ones go in the groups of statements governed by the conditionals; so, in the example above, the return result statement is evaluated once the conditional is done,  no matter which  branch  of the conditional is evaluated.

 

Posted Date: 8/9/2012 7:02:10 AM | Location : United States







Related Discussions:- Conditionals- booleans, Assignment Help, Ask Question on Conditionals- booleans, Get Answer, Expert's Help, Conditionals- booleans Discussions

Write discussion on Conditionals- booleans
Your posts are moderated
Related Questions
Finally! After years of adding unimportant sports, the IOC has finally added Shoe Tying to the Olympics. And you’ve been selected to write the software to handle the judging of t

Common Errors and Messages Here are some common Python errors  and error  messages to look  out for. Please let us give if you have any favorite additions for this list.


Environments in Python Generally, Python establishes the following binding environments: 1.  builtin     : the mother of all environments: it contains the de?nitions of

In English, specify a representation of the board game in Python. The representation should capture the entire state of the game at one point in time. It may be helpful to first fi

I have python game project which is due by next Tuesday. Do you think that I can get it on time if I order today?

Primitives, Composition, Abstraction, and Patterns   We will  start  by thinking about  how  the  PCAP  framework applies to computer programs, in general. We may do that by

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

Write a Python program to accomplish the following. Use modular design. Include at least 3 functions: one that returns zero values, one that returns one value, and one that retu

how do you make an if and else statment work in pytho?