CS1302 Introduction to Computer Programming
while condition:
block
Example: print the square of all odd numbers smaller than 10.
Definite Loops:
we can inspect the code and determine the exact number of iterations the loop will perform.
Example: the loop will perform n times.
Indefinite Loops:
we cannot predict at any point during the loop’s execution how many iterations the loop will perform.
Example: the loop will end only if the user input 10.
range( begin,end,step )
begin = 0, step = 1 by default.
Example: print all the elements in a list.
Example: given list1 and list2, create a new list whose elements are all the combinations of [m, n], where m comes from list1 and n comes from list2.
break:
the program immediately exits from the body of the loop.
Example: terminate the loop earlier when the index is 3 (before index > 4 and unsatisfy the while condition).
continue:
skips rest of the body in the loop for this iteration, and immediately checks the loop’s condition to determine whether enter next iteration.
Example: do not print when n == 2.
The code in a loop’s else block will execute when the loop exits normally, and not execute if the loop terminates due to a break statement.
In this example, print(count, ">=5") will execute.
In this example, print("Loop ends normally.") will not execute.
An infinite loop is a loop that executes its block of statements repeatedly until the user forces the program
to quit.
Example: while True
(the only ways to exit the loop is via a break statement, return statement, or a sys.exit call embedded somewhere within its body.
Should avoid creating infinite loops by accident.
Add conditions in while statement to control the number of iterations.