# While loops#

while loops repeat instructions until certain condition is False (while the condition is True). The syntax is as follows:

    while condition:
# Some code to be executed repeatedly as long as condition is True

# Some more code to be executed once the while loop is over, executed once


Some while loops are infinite, where the condition never becomes False. A while loop, like if statements, needs the code to be indented.

## Example#

counter = 0  # Set counter
print("Initial counter is: ", counter)

print("Entering while loop")
while counter <= 10:
# Increase counter by 1 as long as it is <= 10
counter += 1

print(counter)

print("While loop finished.")
print("Final counter is: ", counter)

Initial counter is:  0
Entering while loop
1
2
3
4
5
6
7
8
9
10
11
While loop finished.
Final counter is:  11


## Exercises#

• Write a program that prints all Fibonacci numbers smaller than 50. An example of a Fibonacci sequence is the following:

$F_0 = 0,\quad F_1 = 1, \quad F_{n}=F_{n-1}+F_{n-2}.$

• Create a while loop to find Celsius temperatures for Fahrenheit temperatures between 20$$^\circ$$F and 80$$^\circ$$F at 5$$^\circ$$F increments. The Fahrenheit-Celsius conversion formula is:

$T_{Celsius} = \frac{5}{9}*(T_{Fahrenheit}-32).$