Udacity CS101 Unit2-26 Break Solution and Notes

Udacity CS101, Unit 2-26, Equivalent Loops Quiz, Spoiler Alert - My notes after watching the solution to this quiz - Udacity Forums
This was posted to the Udacity Forum at http://forums.udacity.com/questions/100051420/spoiler-alert-my-notes-after-watching-the-solution-to-this-quiz#cs101
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print "Udacity Quiz, Lesson 2, Section 26"
print "The basic 'while' loop"
print "- Quiz: https://www.udacity.com/course/viewer#!/c-cs101/l-48753036/e-48714355/m-48684618"
print "- Answer: https://www.udacity.com/course/viewer#!/c-cs101/l-48753036/e-48714355/m-48700404"
print "A good link regarding 'loop control': break, continue, and pass"
print "http://www.tutorialspoint.com/python/python_loop_control.htm"

print ""
print "The original"
print "Which of the below produce the same output as this."
i = 0
variable1 = 3
while i <= variable1:
    i = i + 1
    print i
print""

print "1. Using 'break'"
while i <= variable1:
    if False:
        break
    i = i + 1
    print i
print "This is equivalent because it will never 'break'."
print""

print "2. While True"
print "not equivalent because it prints 1 and then 'breaks'"
i = 0
variable1 = 3
while i <= variable1:
    i = i + 1
    print i
    break
print""

print "3. Using 'break'"
i = 0
variable1 = 3
while True:
    if i <= variable1:
        break
    i = i + 1
    print i
print "This is not equivalent, because in the original the "
print "command is executed 'while' the test is true."
print "in this (#3) it 'breaks' if the test is true"
print "so (in this case) it will not print anything."
print""

print "'Correcting' #3. 'if not' "
print "So now it is equivalent"
i = 0
variable1 = 3
while True:
    if not i <= variable1: # "if i" changed to "if not i"
        break
    i = i + 1
    print i
print " 'if i <= variable1:' changed to 'if not i <= variable1:' "
print""



print "4. Using 'break'"
i = 0
variable1 = 3
while i <= variable1:
    i = i + 1
    print i, "output by main loop"
    if i <= variable1:
       i = i + 1
       print i, "output by 'if' statement in sub-loop"
    else:
        break
print "This is equivalent, because the 'if statement'"
print "sub-loop simply does the same work as the main loop"
print "the main loop prints 1, the sub loop prints 2, then the main loop prints 3"
print""