[Tutor] Just started Python

Johnson Tran aznjonn at me.com
Thu Apr 28 00:51:10 CEST 2011


Yeah, I'll be honest I did not really understand the float concept, thanks for explaining that =). So basically model does not have to be defined in try: because it does not need to be told to be put into point number?

Okay so my final program is:

model=raw_input("What kind of car do you drive?")
gallons=raw_input("How many gallons have you driven?")
miles=raw_input("How many miles have you driven?")

try:
    number1 = float(gallons)
    number2 = float(miles)
except ValueError:
    print "some values are wrong type."
else:
    print "Your average number of miles to gallons is",
    print number1 / number2


Thanks guys created my first successful program ! =D







On Apr 27, 2011, at 3:13 PM, Alan Gauld wrote:

> 
> "Johnson Tran" <aznjonn at me.com> wrote
> 
>> Thanks for the reply Alan and Noah, I really appreciate
>> the help. I am really trying to understand this although
>> still cannot seem to grasp it all.
> 
> Lets step back a stage.
> 
> Do you understand what float() does?
> 
>> I have modified my program although now it seems
>> to be giving me the wrong answer with the correct
>> answer when I input any value.
>> 
>> model=raw_input("What kind of car do you drive?")
>> gallons=raw_input("How many gallons have you driven?")
>> number1 = float (gallons)
> 
> This is taking the value typede by the user and trying
> to convert it from a string to a floating point number - that is,
> a decimal value
> 
>> miles=raw_input("How many miles have you driven?")
>> number2 = float (miles)
> 
> Similarly this converts the input string to a decimal value,
> if possible.
> 
>> try:
>>  model=float(model)
> 
> But what is this doing?
> 
> It is trying to convert the model of car to a decimal value.
> Unless trhe car is a Porche 911 or similar its unlikely
> to succeed! If its a Toyota Prius it will fail with a ValueError
> exception.
> 
>> except ValueError:
>>  print "I cannot compute your total miles to gallon with those values."
> 
> And therefore print this message
> 
>> else:
>>  print "Your average number of miles to gallons is",
>> print number1 / number2
> 
> The second print needs to be inside the else too.
> 
>> What kind of car do you drive?fire
>> How many gallons have you driven?10
>> How many miles have you driven?5
>> I cannot compute your total miles to gallon with those values.
> 
> Because it cannot convert 'fire' to a decimal value.
> 
> HTH,
> 
> 
> -- 
> Alan Gauld
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> 
> 
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