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Section 6.12 Write Code Questions

Warning 6.12.1.

Be careful not to create infinite loops, as they will cause the page to freeze.

Activity 6.12.1.

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()

Activity 6.12.2.

The following code will loop way too many times. Change one line to make the loop only have five iterations.

Activity 6.12.3.

Make 5 changes to the code below to correctly print a count up from -10 to 0, including 0.
Solution. 
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()

Activity 6.12.4.

Finish lines 1 and 5 so that the following code correctly prints every integer from -5 to -1, including -1.

Activity 6.12.5.

Complete the code on lines 4 and 6 so that it prints the number 6.
Solution. 
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()

Activity 6.12.6.

The code below is supposed to print an estimate of the square root of a number (target). You are given an initial guess of 2. However, the indention is wrong on 4 lines. Fix these errors to find the estimate.

Activity 6.12.7.

Create code to print an estimate of the square root of a number (target). You are given an initial guess of 2.

Activity 6.12.8.

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Activity 6.12.9.

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. 
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()

Activity 6.12.10.

The program below is supposed to print the times tables from 1 to 3, but there are 6 errors. Fix the errors.

Activity 6.12.11.

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

Activity 6.12.12.

Rewrite the following code to use a while loop instead of a for loop to calculate the value of ten factorial.

Activity 6.12.13.

Using the blocks below, create code to calculate the value of ten factorial.

Activity 6.12.14.

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