==== 9/18/13 ====

Modulus Operator gives remander after division. For example.



In [1]:

    
5 % 2









    Out[1]:





1



In [2]:

    
4 % 2









    Out[2]:





0

===== Booleans =====



In [3]:

    
5 < 6









    Out[3]:





True



In [4]:

    
5 != 6









    Out[4]:





True



In [8]:

    
3 + 1 == 2 + 2









    Out[8]:





True



In [9]:

    
not True









    Out[9]:





False



In [10]:

    
not False









    Out[10]:





True



In [12]:

    
True and False









    Out[12]:





False



In [19]:

    
True and not (True or False) and not False









    Out[19]:





False



In [20]:

    
False is not True









    Out[20]:





True



In [21]:

    
4 % 2 == 0









    Out[21]:





True



In [22]:

    
n = 5
n % 2 == 0









    Out[22]:





False



In [23]:

    
17 and False









    Out[23]:





False



In [24]:

    
-1 and True









    Out[24]:





True



In [25]:

    
0 and True









    Out[25]:





0



In [26]:

    
True and 0









    Out[26]:





0



In [27]:

    
0 or True









    Out[27]:





True



In [28]:

    
0 or False









    Out[28]:





False



In [29]:

    
'fred' and True









    Out[29]:





True



In [30]:

    
'' and True









    Out[30]:





''



In [31]:

    
'' or True









    Out[31]:





True



In [33]:

    
None and True



In [34]:

    
None or True









    Out[34]:





True

==== Conditionals ====



In [36]:

    
name = 'bob'
if name == 'fred':
    print "Hi fred!"



In [40]:

    
x = 99
if x > 10:
    z = 9
    x = x + z
print z



In [43]:

    
name = 'susan'
if name == 'jane' or name == 'susan':
    print "Hello " + name
else:
    print "Who are you?"









    



Hello susan



In [48]:

    
name = 'fred'
if name == 'tom':
    print "Hello Tom"
elif name == 'jim':
    print "Hello Jim"
else:
    print "I don't know any "+name









    



I don't know any fred



In [49]:

    
x = 7
y = 6
if x == y:
    print 'x and y are equal'
else:
    if x < y:
        print 'x is less than y'
    else:
        print 'x is greater than y'









    



x is greater than y

http://projecteuler.net/problem=1



In [52]:

    
x = 986469
if x % 3 == 0:
    print "Divisible by 3"
elif x % 5 == 0:
    print "Divisible by 5"









    



Divisible by 3

==== Recursion ====

Basically, the act of a function calling itself. For example, see this function calls itself.



In [53]:

    
def countdown(n):
    if n <= 0:
        print 'Blastoff!'
    else:
        print n
        countdown(n-1)
countdown(5)









    



5
4
3
2
1
Blastoff!

Recursion is a useful tool in solving some problems (mostly the ones where a "divide and conquer" strategy are useful), however, it can be error prone and should be used with caution.

==== Gettin INPUT ====

A simple function to get input from the user is raw_input. Be aware that the value returned from raw_input is ALWAYS a string! So if you need a number, you must convert the value to a number using one of the conversion functions ( int() or float() ).



In [58]:

    
name = raw_input("What's your name:")
age = raw_input("How old are you:")
age = int(age)
print "Hello "+name
if int(age) > 22:
    print "Boy you are old"
print type(age)









    



What's your name:ted
How old are you:40
Hello ted
Boy you are old
<type 'int'>



In [ ]: