Python Loops
Python has two primitive loop commands:
- while loops
- for loops
The while Loop
With the while loop we can execute a set of statements as long as a condition is true.
Example
Print i as long as i is less than 6:i = 1
while i < 6:
print(i)
i += 1
Output:
1
2
3
4
5
Note: remember to increment i, or else the loop will continue forever.
The while loop requires relevant variables to be ready, in this example we need to define an indexing variable, i, which we set to 1.
The break Statement
With the break statement we can stop the loop even if the while condition is true:
Example
Exit the loop when i is 3:i = 1
while i < 6:
print(i)
if i == 3:
break
i += 1
Output:
1
2
3
The continue Statement
With the continue statement we can stop the current iteration, and continue with the next:
Example
Continue to the next iteration if i is 3:i = 0
while i < 6:
i += 1
if i == 3:
continue
print(i)
#Note that number 3 is missing in the result
Output:
1
2
4
5
6
The else Statement
With the else statement we can run a block of code once when the condition no longer is true:
Example
Print a message once the condition is false:i = 1
while i < 6:
print(i)
i += 1
else:
print(“i is no longer less than 6”)
Output:
1
2
3
4
5
i is no longer less than 6