Loops are an important control structure
something about python loops
For Loop
The iteration variable i is assigned to the list of given values.
for i in range(10):
print i
It is resilient against modifications during a single iteration:
for k in range(-5,5):
print "k=", k
k = k + 2 * k + 1
print "modified k=", k
While Loop
j = 5
while j >= 0:
print j
j -= 1
Iteration Loop
who = ["boy", "girl", "teacher", "banana"]
for name in who:
print name.title()
The iterator enumerate yields
tuples of (<index number>, element).
The <index number> zero and increments by 1 for each element
in the list
cities = ["peking", "paris", "new york", "casablanca"]
for index, city in enumerate(cities):
print index, city
For-else construction
This is useful to iterate until a condition is met.
for x in [2,5,7,11,15,23,31,97]:
if x % 3 == 0:
print x, "is divisible by 3"
break
else:
print "no number was divisible by 3"
Task: Change the 15 to 17 in the example above and try again.
Mentioned in