while loop will run until a boolean test returns false.
while condition: indented body lines
The loop checks the given condition. If
False, the program continues beyond the loop. If
True, the code in the loop is executed. Once the code inside the loop is finished, the condition is checked again and the cycle repeats if
for loop runs a piece of code once per item in a collection.
>>> for num in [2, 4, 6, 8]: ... print(num) 2 4 6 8
In the above example, a
for loop iterates over list
[2, 4, 6, 8]. In each iteration, the current list item is assigned to the keyword
num and is used to print the current number.
range function forms a common code pattern with
for i in range(10): print(i)
for i in range(len(s)): print(s[i])
In the first example above, the loop will print 10 numbers from 0-9 inclusive based off the iterable object returned by
range(). In the second example,
range(len(s)) creates an iterable corresponding to each of a string’s indices. The loop then prints out each character on a new line.
continue directives provide powerful ways to control the flow and logic of loops.
break directive will exit a loop without executing any additional code and without re-starting the loop.
continue directive will skip to the next iteration of a loop without executing any additional code for that iteration.