In [77]:
#today we are going to cover while loops.
#While loops are very similar to for loops. 
#To review, what does this print?
for x in range(5):
    print x
0
1
2
3
4
In [86]:
#How do I do the same thing in while loops
#while ....:
    #do something
#the code indented in the next line after the while loop is only 
#executed if the thing next to the while statement evaluates to True.

#Example
x=0
while True:
    x += 1 #x=3
    if x==3:
        continue
    print x
    if x==5:
        break
#what does this print?
#In this case, True is always True, 
#so the while loop executes until we break. 
1
2
4
5
In [88]:
#Example
x=0
while x<=5:
    x += 1 
    if x==3:
        continue
    print x
    #if x==5:
    #    break
1
2
4
5
6
In [91]:
#what does this print?
y=0
x = []
while y <=5:
    print y      #y=4
    y += 1       #y=5
    x += [y]     #x=[1,2,3,4,5]
    print x      
 
#x += [y] 
print x 
0
[1]
1
[1, 2]
2
[1, 2, 3]
3
[1, 2, 3, 4]
4
[1, 2, 3, 4, 5]
5
[1, 2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6]
In [92]:
#Example: Both of these code examples print 
#only the odd numbers between 0 and 5.
myList = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
for x in myList:
    if x > 5: 
        break
    elif x%2 == 0:
        continue
    else:
        print x
1
3
5
In [93]:
# Example with while loop. What does this do?
x=0
while True:
    if x > 5: 
        break
    elif x%2 == 0:
        x += 1
        continue
    else:
        print x
    x += 1
1
3
5
In [ ]:
# Example with while loop. What does this do?
x=0
while True:
    if x > 5: 
        break
    elif x%2 == 0:
        #x += 1 <---now what happens if I don't have this line?
        continue
    else:
        print x
    x += 1
    
#You should always be careful when you use while loops.
#Because if you don't tell it when to stop, a while loop
#can go on forever. 
In [ ]:
# Example with while loop. What does this do?
x=0
while True:
    if x > 5: 
        break
    elif x%2 == 0:
        x += 1 
        continue
    else:
        print x
    x += 1 #<---now what happens if I don't have this line?