Python Looping

while Loop
An if statement is run once if its condition evaluates to TRUE and never if it evaluates to FALSE.

A while statement is similar, except it can be run more than once. The statements inside it are repeatedly executed as long as the condition holds. Once it evaluates to FALSE, the next section of code is executed.

i = 1
while i<=4:
  print (i)
  i+=1
print ('End') 

Output:

>>>
1
2
3
4
End
>>>

The infinite loop is a particular kind of the while loop; it never stops running. Its condition always remains TRUE.

while 1 == 1:
 print ('in the loop')

To end the while loop prematurely, the break statement can be used. The break statement causes the loop to finish immediately when encountered inside a loop.

i = 0
while 1==1:
  print (i)
  i += 1
  if i >=3:
    print('breaking')
    break;
print ('finished')    

Output:

>>>
0
1
2
3
breaking
finished
>>>

Another statement that can be used within loops is continue.

Unlike break, continue jumps back to the top of the loop rather than stopping it.

i = 0
while True:
  i+=1
  if i == 2:
    printf ('skipping 2')
    continue
  if i == 5:
    print ('breaking')
    break
  print (i)
print ('finished')  

Output:

>>>
1
skipping 2
3
4
breaking
finished
>>>

for Loop

n = 9
for i in range (1,5):
  ml = n * i
  print ("{} * {} = {}".format (n, i, ml))

Output:

>>>
9 * 1 = 9
9 * 2 = 18
9 * 3 = 27
9 * 4 = 36
>>>