Control flow

Some basic control flow statements.

for loop

a_list = ["a", "b", "c", "d"]

## print both index and item
for n, item in enumerate(a_list):
    print(n, item)
## after loop
else:
    print('done!')

0 a
1 b
2 c
3 d
done!

if else

a_list = ["a", "b", "c", "d"]

## if/else within loop
for n, item in enumerate(a_list):
    if n % 2 == 0:
        print(n, item)
    else:
        print(item)
## after loop
else:
    print('done!')

0 a
b
2 c
d
done!

while

import random

running = True
while running:
    x = random.randint(0,10)
    print(x)
    if x > 5:
        print(x, ' is over 5')
        running = False

0
9
9 is over 5

break, continues

• break, breaks out of the innermost loop.
• continue, continues with the next iteration of the loop.

for num in range(5):
    if num < 4:
        print(num, "< 4")
    else:
        break

0 < 3
1 < 3
2 < 3

for num in range(5):
    if num % 2 == 0:
        print(num, "even number")
        continue
    print(num, "odd number")

0 even number
1 odd number
2 even number
3 odd number
4 even number