Python Program help with IF Else

[mdmytryk]

Hey, im new to computer programming as well as python, so please be gentle. Im working on a program that will calculate grades. When a value other than A,B,C,D, or F is entered, i want the program to give an error message. This is what i have come up with:

[CODE=python]
print "welcome to the GPA calculator"

totalpoints=0.0

name=raw_input( "please enter the name of the student ")
grade=raw_input ("please enter "+name+ "'s English grade ")

if grade == "A" or "a":

totalpoints = totalpoints + 4.0*3

elif grade == "B "or "b":

totalpoints = totalpoints + 3.0*3

elif grade == "C" or "c":

totalpoints = totalpoints + 2.0*3

elif grade == "D" or "d":

totalpoints = totalpoints + 1.0*3

elif grade == "F" or "f":

totalpoints = totalpoints + 0.0*3

else:

print "Imput is not correct"
[/CODE]


The when a value is entered that is not A...F, the "imput is not correct" does not display. Could somebody please tell me what i am doing wrong here? Thanks alot,
mike

[bartonc]

[CODE=python]
if (grade == "A") or (garde == "a"):

# or

if grade in "Aa":

# or

if grade.lower() == 'a':

# or

if grade.upper() == 'A':
#...
print totalpoints[/CODE]

[mdmytryk]

that was amazingly fast, i really appreciate the help.

mike

[bartonc]

that was amazingly fast, i really appreciate the help.

mike

Watch out! I was editing while you were reading...

[mdmytryk]

How would i write code that would take me from the end of the code back to the beginning? I imagine this would have to be some kind of while loop, but i cant put my finger on how i would incorporate it into the existing code.

EDIT

nevermind, i jumped the gun asking for help, i think i figured it out.

thanks

[bartonc]

How would i write code that would take me from the end of the code back to the beginning? I imagine this would have to be some kind of while loop, but i cant put my finger on how i would incorporate it into the existing code.

EDIT

nevermind, i jumped the gun asking for help, i think i figured it out.

thanks

That's OK. Here are some ideas for you to play with:[CODE=python]
print "welcome to the GPA calculator"


### some basic input checking:
##while True: # always repeat #
## nClasses = raw_input("plea se enter the number of classes for the student ")
## try:
## nGrades = int(nClasses) # try to convert to an integer
## break # break out of the loop
## except ValueError: # couldn't convert
## pass # do nothing

# start with a list of classes #
ClassNames = ('English', 'Math', 'History')
nClasses = len(ClassNames)
Grades = tuple("ABCDF")

# get the student's name
name = raw_input("plea se enter the name of the student ")

totalpoints=0.0

# Now, loop on the 'Classes' list - actaully a tuple of names
for className in ClassNames:
grade = None
while grade not in Grades:
# we'll use string formatting instead of addition
# variables are plugged into the '%s' locations #
grade = raw_input("plea se enter %s's %s grade " %(name, className))
grade = grade.upper()

if grade == "A":
totalpoints = totalpoints + 4.0

elif grade == "B":
totalpoints = totalpoints + 3.0

elif grade == "C":
totalpoints = totalpoints + 2.0

elif grade == "D":
totalpoints = totalpoints + 1.0

## no need to add zero
## elif grade == "F":
## totalpoints = totalpoints + 0.0

print "The GPA is %.1f" %(totalpoints/nClasses)[/CODE]

[mdmytryk]

I finished writing the program i was working on and was wondering if i could get some feedback on it. This was an assignment for a class, so some of the values were set by the professor, such as the number of classes, the lame greetings, etc. As far as i know, the program works, although im not sure how orthodox my coding is.
[CODE=python]
student=0
while student==0:

print "welcome to Mike's GPA calculator!"

name=raw_input( "please enter the name of the student: ")
totalpoints=0.0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s English grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0

count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Math grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Chemistry grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Physics grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0

totalpoints = totalpoints/10
print "The gpa for "+name+" is",totalpoin ts


ask=raw_input(" would you like to calculate another GPA?: y/n:" )

if (ask == "y") or (ask == "Y"):
student=0
else:
student=1

raw_input("\n\n Thank you for using Mike's GPA calculator. Please press Enter to Exit.")[/CODE]

[ilikepython]

I finished writing the program i was working on and was wondering if i could get some feedback on it. This was an assignment for a class, so some of the values were set by the professor, such as the number of classes, the lame greetings, etc. As far as i know, the program works, although im not sure how orthodox my coding is.

student=0
while student==0:

print "welcome to Mike's GPA calculator!"

name=raw_input( "please enter the name of the student: ")
totalpoints=0.0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s English grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0

count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Math grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Chemistry grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Physics grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0

totalpoints = totalpoints/10
print "The gpa for "+name+" is",totalpoin ts


ask=raw_input(" would you like to calculate another GPA?: y/n:" )

if (ask == "y") or (ask == "Y"):
student=0
else:
student=1

raw_input("\n\n Thank you for using Mike's GPA calculator. Please press Enter to Exit.")

Use:
[code=python]
if ask.lower() == "y":
... ...
[/code]
instead of
[code=python]
if (ask == "Y") or (ask == "y"):
... ...
[/code]
Haven't checked it thouroughly though.

[ilikepython]

I finished writing the program i was working on and was wondering if i could get some feedback on it. This was an assignment for a class, so some of the values were set by the professor, such as the number of classes, the lame greetings, etc. As far as i know, the program works, although im not sure how orthodox my coding is.

student=0
while student==0:

print "welcome to Mike's GPA calculator!"

name=raw_input( "please enter the name of the student: ")
totalpoints=0.0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s English grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0

count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Math grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*3
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*3
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*3
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*3
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*3
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Chemistry grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0
count=0
while count==0:

grade=raw_input ("please enter "+name+ "'s Physics grade: ")

if (grade == "A") or (grade == "a"):
totalpoints = totalpoints + 4.0*2
count = 1
elif (grade == "B") or (grade == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif (grade == "C") or (grade == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif (grade == "D") or (grade == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif (grade == "F") or (grade == "f"):
totalpoints = totalpoints + 0.0*2
count =1
else:
print "The input you have entered is not valid"
count = 0

totalpoints = totalpoints/10
print "The gpa for "+name+" is",totalpoin ts


ask=raw_input(" would you like to calculate another GPA?: y/n:" )

if (ask == "y") or (ask == "Y"):
student=0
else:
student=1

raw_input("\n\n Thank you for using Mike's GPA calculator. Please press Enter to Exit.")

I don't think you need all that code:
[code=python]
courses ["Physics", "Chemistry" , "Math", "English"]
student=0
while student==0:

print "welcome to Mike's GPA calculator!"
name=raw_input( "please enter the name of the student: ")
totalpoints=0.0
for course in courses:
count=0
while count==0:
grade=raw_input ("please enter %s's %s grade: " % (name, course))

if grade.lower() == "a":
totalpoints = totalpoints + 4.0*2
count = 1
elif grade.lower() == "b"):
totalpoints = totalpoints + 3.0*2
count = 1
elif grade.lower() == "c"):
totalpoints = totalpoints + 2.0*2
count = 1
elif grade.lower() == "d"):
totalpoints = totalpoints + 1.0*2
count = 1
elif grade.lower() == "f"):
totalpoints = totalpoints + 0.0*2
count = 1
else:
print "The input you have entered is not valid"
#count = 0 no need to set it; if it goes to else; count is not 1

totalpoints = totalpoints/10
print "The gpa for "+name+" is",totalpoin ts


ask=raw_input(" would you like to calculate another GPA?: y/n:" )

if (ask == "y") or (ask == "Y"):
student=0
else:
student=1
[/code]
That should work.

[bartonc]

I finished writing the program i was working on and was wondering if i could get some feedback on it. This was an assignment for a class, so some of the values were set by the professor, such as the number of classes, the lame greetings, etc. As far as i know, the program works, although im not sure how orthodox my coding is.

Orthodox?.. Well, not quite. You are close, but the loop inside a loop (as suggested by others) is more like what you want to shoot for.

HERE'S the BIGGIE: You must use CODE tags! Instructions are on the right hand side of the page while you are posting or replying.

Thanks.

[mdmytryk]

Thanks for the help guys, i have defiantly learned a thing or two. Last question, im sure my simpleton questions are getting a little tedious. I see that i should use a loop within a loop, makes sense. However, some of the classes in this program are 2 credit hour, and some are 3.

# this is the 2 credit hour class, notice how its multiplied by 2
totalpoints = totalpoints + 3.0*2

# this is the 3 credit hour class.
totalpoints = totalpoints + 3.0*3

Two of the classes are 2 credit hour, and the other two are 3. Would it be easier to use 2 separate loops, or would it make more sense to not have the values hard coded?

Thanks

[ilikepython]

Thanks for the help guys, i have defiantly learned a thing or two. Last question, im sure my simpleton questions are getting a little tedious. I see that i should use a loop within a loop, makes sense. However, some of the classes in this program are 2 credit hour, and some are 3.

# this is the 2 credit hour class, notice how its multiplied by 2
totalpoints = totalpoints + 3.0*2

# this is the 3 credit hour class.
totalpoints = totalpoints + 3.0*3

Two of the classes are 2 credit hour, and the other two are 3. Would it be easier to use 2 separate loops, or would it make more sense to not have the values hard coded?

Thanks

It is still possible to use a single loop. You could have the credit hour as part of the list you use for the loop:
[code=python]
courses = [("Math", 2), ("Science", 3), ("English", 3), ("Chemistry" , 2)]

for (course, credit) in courses:
... then ...
totalpoints += 3.0 * credit
[/code]
You could also rewrite the program without all those if statements to determine the grade:
[code=python]
import string
grades = [4.0, 3.0, 2.0, 1.0]

for (course, credit) in courses:
grade = raw_input("Ente r grade: ")
totalpoints += grades[string.lowercas e.index(grade.l ower())] * credit
[/code]
See if that works for you.

[bartonc]

Thanks for the help guys, i have defiantly learned a thing or two. Last question, im sure my simpleton questions are getting a little tedious. I see that i should use a loop within a loop, makes sense. However, some of the classes in this program are 2 credit hour, and some are 3.

# this is the 2 credit hour class, notice how its multiplied by 2
totalpoints = totalpoints + 3.0*2

# this is the 3 credit hour class.
totalpoints = totalpoints + 3.0*3

Two of the classes are 2 credit hour, and the other two are 3. Would it be easier to use 2 separate loops, or would it make more sense to not have the values hard coded?

Thanks

Now you will truly see (and you questions are by no means tedious) the flexibility of list:[CODE=python]
print "welcome to the GPA calculator"


# start with a list of classes #
ClassNames = ('Physics', 'Chemistry', 'Math', 'English')
# assign each class a credit hour value #
CredHoursDict = dict(zip(ClassN ames, (2, 2, 3, 3,)))
print CredHoursDict
##nClasses = len(ClassNames)
Grades = tuple("ABCDF")

# get the student's name
name = raw_input("plea se enter the name of the student ")

totalpoints=0.0
totalCreditHour s = 0

# Now, loop on the 'Classes' list - actaully a tuple of names
for className in ClassNames:
grade = None
while grade not in Grades:
# we'll use string formatting instead of addition
# variables are plugged into the '%s' locations #
grade = raw_input("plea se enter %s's %s grade " %(name, className))
grade = grade.upper()

credHours = CredHoursDict[className]
totalCreditHour s += credHours

if grade == "A":
totalpoints = totalpoints + (4.0 * credHours)

elif grade == "B":
totalpoints = totalpoints + (3.0 * credHours)

elif grade == "C":
totalpoints = totalpoints + (2.0 * credHours)

elif grade == "D":
totalpoints = totalpoints + (1.0 * credHours)

## no need to add zero
## elif grade == "F":
## totalpoints = totalpoints + 0.0

print "The GPA is %.1f" %(totalpoints/totalCreditHour s)[/CODE]

[bartonc]

It is still possible to use a single loop. You could have the credit hour as part of the list you use for the loop:
[code=python]
courses = [("Math", 2), ("Science", 3), ("English", 3), ("Chemistry" , 2)]

for (course, credit) in courses:
... then ...
totalpoints += 3.0 * credit
[/code]
You could also rewrite the program without all those if statements to determine the grade:
[code=python]
import string
grades = [4.0, 3.0, 2.0, 1.0]

for (course, credit) in courses:
grade = raw_input("Ente r grade: ")
totalpoints += grades[string.lowercas e.index(grade.l ower())] * credit
[/code]
See if that works for you.

I also like the tuple (humble beginnings of a true object) to define a "course".
I do not, however, find any redeeming qualities in this usage:

grades[string.lowercase.index(grade.lower())]

Sorry, my friend:

• too many functions squished into one line (there is no advantage in doing so)

[bartonc]

I also like the tuple (humble beginnings of a true object) to define a "course".

In fact, I like it so much that I did a little rewrite:[CODE=python]
print "welcome to the GPA calculator"


# start with a list of classes #
ClassNames = ('Physics', 'Chemistry', 'Math', 'English')
# assign each class a credit hour value #
CourseTupleList = zip(ClassNames, (2, 2, 3, 3,))
print CourseTupleList
##nClasses = len(ClassNames)
Grades = tuple("ABCDF")

# get the student's name
name = raw_input("plea se enter the name of the student ")

totalpoints=0.0
totalCreditHour s = 0

# Now, loop on the 'Courses' list - actaully a list of two-tuple of names, credit hours
for className, credHours in CourseTupleList :
grade = None
while grade not in Grades:
# we'll use string formatting instead of addition
# variables are plugged into the '%s' locations #
grade = raw_input("plea se enter %s's %s grade " %(name, className))
grade = grade.upper()

totalCreditHour s += credHours

if grade == "A":
totalpoints = totalpoints + (4.0 * credHours)

elif grade == "B":
totalpoints = totalpoints + (3.0 * credHours)

elif grade == "C":
totalpoints = totalpoints + (2.0 * credHours)

elif grade == "D":
totalpoints = totalpoints + (1.0 * credHours)

## no need to add zero
## elif grade == "F":
## totalpoints = totalpoints + 0.0

print "The GPA is %.1f" %(totalpoints/totalCreditHour s)[/CODE]
welcome to the GPA calculator
[('Physics', 2), ('Chemistry', 2), ('Math', 3), ('English', 3)]
please enter the name of the student Barton
please enter Barton's Physics grade a
please enter Barton's Chemistry grade b
please enter Barton's Math grade c
please enter Barton's English grade b
The GPA is 2.9