Warning 6.11.1.
Be careful not to create infinite loops, as they will cause the page to freeze.
Section 6.11 Write Code Questions
Checkpoint 6.11.2.
Fix the 5 errors in the code below to return a countdown of the numbers from 10 to 0, including 0.
Solution.
Fix the 5 errors in the code below to return a countdown of the numbers from 10 to 0, including 0.
def countdown():
counter = 10
answer = ""
# Keep running loop until counter equals 0 (use <=)
# Use correct variable name (counter is lowercase)
while counter >= 0:
answer = answer + str(counter) + " "
# Decrement to lower the counter
counter = counter - 1
# Keyword return is lowercase
return answer
# Call correct function name (countdown)
countdown()
====
from unittest.gui import TestCaseGui
class myTests(TestCaseGui):
def testOne(self):
output = countdown()
self.assertEqual(output,"10 9 8 7 6 5 4 3 2 1 0 ")
myTests().main()
Checkpoint 6.11.3.
The following code will loop way too many times. Change one line to make the loop only have five iterations.
Checkpoint 6.11.4.
Make 5 changes to the code below to correctly print a count up from -10 to 0, including 0.
Solution.
Make 5 changes to the code below to correctly print a count up from -10 to 0, including 0.
output = ""
# Start x at -11 so it stays under 0
x = -11
# First line of a loop ends with a colon (:)
while x < 0:
# Since the iteration variable is negative, increase the count
x = x + 1
# Output reassignment is within the loop
output = output + str(x) + " "
# Close print parentheses
print(output)
====
from unittest.gui import TestCaseGui
class myTests(TestCaseGui):
def testOne(self):
self.assertEqual(output,"-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 ")
myTests().main()
Checkpoint 6.11.5.
Finish lines 1 and 5 so that the following code correctly prints every integer from -5 to -1, including -1.
Checkpoint 6.11.6.
Complete the code on lines 4 and 6 so that it prints the number 6.
Solution.
Complete the code on lines 4 and 6 so that it prints the number 6.
x = 3
i = 0
while i < 3:
# Increase x by 1 for each run of the loop
x = x + 1
i = i + 1
# Print the x variable
print(x)
====
from unittest.gui import TestCaseGui
class myTests(TestCaseGui):
def testOne(self):
self.assertEqual(x,6)
myTests().main()
Checkpoint 6.11.7.
This function currently takes a start and stop argument and uses a for loop to find the sum of all the numbers between them (inclusive). Change the for loop to a while loop while still using the same parameters.
Solution.
This function currently takes a start and stop argument and uses a for loop to find the sum of all the numbers between them (inclusive). Change the for loop to a while loop while still using the same parameters.
def sumFunc(start, stop):
sum = 0
# Create an iteration variable, initialized to the start argument
num = start
# Use while loop until iteration variable is less than
# or equal to stop argument
while num <= stop:
# Add number to sum
sum = sum + num
# Increase iteration variable
num += 1
# Return the sum
return sum
print(sumFunc(1,10))
====
from unittest.gui import TestCaseGui
class myTests(TestCaseGui):
def testOne(self):
self.assertEqual(sumFunc(1, 10),55,"Tested sumFunc on inputs 1 and 10")
self.assertEqual(sumFunc(10, 3),0,"Tested sumFunc on inputs 10 and 3")
self.assertEqual(sumFunc(-5, 0),-15,"Tested sumFunc on inputs 20 and 50")
self.assertEqual(sumFunc(-3, 12),72,"Tested sumFunc on inputs -3 and 12")
myTests().main()
Checkpoint 6.11.8.
The program below is supposed to print the times tables from 1 to 3, but there are 6 errors. Fix the errors.
Checkpoint 6.11.9.
The following code prints the times tables for 1 to 3 using two for loops. Rewrite the program to use a while and a for loop instead.
Solution.
# There are a few different ways this can be done
# One is shown here
for x in range(1, 4):
# Create an iteration variable, starting in the range
y = 1
# Use while loop if the iteration variable is less than 11
while y < 11:
# Print the string
print(str(x) + " * " + str(y) + " = " + str(x * y))
# Increment the iteration variable
y = y + 1
