Re: While loop help
On 04/09/2013 09:49 AM, thomasancill...@gmail.com wrote:
So what would be the proper way to perform a loop of this program. I still
can't quite figure out the best way to do it.
My suggestion... (pseudocode)
# Print a heading/introduction here
while True:
# Print menu, with an added selection to quit
# Get the user's choice (as an int)
if choice == 1:
# Print prompt for this choice
# Enter the value (as float, not int. Why limit your values to ints
anyway?)
# Display the calculated result
elif choice == 2:
# Same procedure as above
elif ... etc
# etc
elif choice == (value for quit):
break# This breaks out of the while loop
else:
# Invalid choice, print error message
# End of loop
Further suggestion:
Since each of the choices use the same basic procedure, it could be written as a separate single
function. It would just need to be passed the appropriate prompt string(s) and conversion
factor. The results display _could_ be in this function also, but that would require passing
even more strings. It would probably be better to simply return the two values (the input value
and the converted value) back to the calling block and print the results there.
Also, don't use the round function here, that does NOT guarantee it will be _printed_ to two
decimal places. Use string formatting in the print statements. For example: (using your
original variable names, and assuming they are now both floats)
old style:
print '%.2f inches = %.2f meters' % (number, calc)
or new style:
print '{:.2f} inches = {:.2f} meters'.format(number, calc)
You also mentioned that you don't like the editor you're using. For a simple substitute you
might try Idle (which normally comes with Python). This gives you the advantage of an
interactive environment as will as an editor. There are many other choices, of course, but as a
newbie you might find this more comfortable than what you're currently using.
I hope this jump-starts your thinking. Keep at it, it's worth the effort.
-=- Larry -=-
--
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Re: While loop help
On Apr 9, 8:47 pm, thomasancill...@gmail.com wrote: ... and if you have any ideas for me to improve my coding that will prevent me from learning python in a sloppy way. I'd like to learn it correctly the first time! Not perhaps a direct answer... Anyways there is style in which python is best used which people coming from more traditional languages are usually not familiar with: its called 'playing around in the interpreter' Here is a small session based on your code that shows this interaction with the interpreter: - $ python Python 2.7.3 (default, Jan 2 2013, 16:53:07) [GCC 4.7.2] on linux2 Type help, copyright, credits or license for more information. def inch2meter(i): return round(i*.254,2) ... inch2meter(1) 0.25 def milliliter2pint(m): return round(number * 0.0021134,2) ... milliliter2pint(100) Traceback (most recent call last): File stdin, line 1, in module File stdin, line 1, in milliliter2pint NameError: global name 'number' is not defined def milliliter2pint(m): return round(m * 0.0021134,2) ... milliliter2pint(100) 0.21 - Notice some things here: 1. I check out the code as soon as its written. So when I cutpasted from your code, without keeping names (m - number) consistent, I get an error, correct it and continue 2. There is not a single print statement. Not just the functions have no prints, even the code that calls them has none. Just call get answer. This point needs to be underscored: In C or java you cannot write any useful code without doing IO ie printf/scanf etc. In python you can and you should try to. -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 04/09/2013 11:44 PM, Larry Hudson wrote:
On 04/09/2013 09:49 AM, thomasancill...@gmail.com wrote:
So what would be the proper way to perform a loop of this program. I still
can't quite figure
out the best way to do it.
My suggestion... (pseudocode)
# Print a heading/introduction here
while True:
# Print menu, with an added selection to quit
# Get the user's choice (as an int)
if choice == 1:
# Print prompt for this choice
# Enter the value (as float, not int. Why limit your values to ints
anyway?)
# Display the calculated result
elif choice == 2:
# Same procedure as above
elif ... etc
# etc
elif choice == (value for quit):
break# This breaks out of the while loop
else:
# Invalid choice, print error message
# End of loop
Further suggestion:
Since each of the choices use the same basic procedure, it could be written as
a separate single
function. It would just need to be passed the appropriate prompt string(s) and
conversion
factor. The results display _could_ be in this function also, but that would
require passing
even more strings. It would probably be better to simply return the two values
(the input value
and the converted value) back to the calling block and print the results there.
Also, don't use the round function here, that does NOT guarantee it will be
_printed_ to two
decimal places. Use string formatting in the print statements. For example:
(using your
original variable names, and assuming they are now both floats)
old style:
print '%.2f inches = %.2f meters' % (number, calc)
or new style:
print '{:.2f} inches = {:.2f} meters'.format(number, calc)
You also mentioned that you don't like the editor you're using. For a simple
substitute you
might try Idle (which normally comes with Python). This gives you the
advantage of an
interactive environment as will as an editor. There are many other choices, of
course, but as a
newbie you might find this more comfortable than what you're currently using.
I hope this jump-starts your thinking. Keep at it, it's worth the effort.
-=- Larry -=-
On a little further thought, I realized the single function I suggested is even easier than I
originally thought -- even with the results printed in the function. Here's an example:
def convert(frm, to, factor):
# frm and to are strings, factor is a float
print 'Converting {} to {}:'.format(frm, to)
value = float(raw_input('How many {}? '.format(frm)))
print '{:.2f} {} is {:.2f} {}'.format(value, frm, value * factor, to)
You would use it like:
convert('inches', 'meters', 0.0254)
or
convert('meters', 'inches', 39.37)
-=- Larry -=-
--
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While loop help
I'm new to learning python and creating a basic program to convert units of measurement which I will eventually expand upon but im trying to figure out how to loop the entire program. When I insert a while loop it only loops the first 2 lines. Can someone provide a detailed beginner friendly explanation. Here is my program. #!/usr/bin/env python restart = true while restart == true: #Program starts here print To start the Unit Converter please type the number next to the conversion you would like to perform choice = input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) #If user enters 1:Program converts inches to meters if choice == 1: number = int(raw_input(\n\nType the amount in Inches you would like to convert to Meters.\n)) operation = Inches to Meters calc = round(number * .0254, 2) print \n,number,Inches =,calc,Meters restart = raw_input(If you would like to perform another conversion type: true\n #If user enters 2:Program converts millimeters to pints elif choice == 2: number = int(raw_input(\n\nType the amount in Milliliters you would like to convert to Pints.\n)) operation = Milliliters to Pints calc = round(number * 0.0021134,2) print \n,number,Milliliters =,calc,Pints restart = raw_input(If you would like to perform another conversion type: true\n) #If user enter 3:Program converts kilometers to miles elif choice == 3: number = int(raw_input(\n\nType the amount in Kilometers you would like to convert to Miles.\n)) operation = Kilometers to Miles calc = round(number * 0.62137,2) print \n,number,Kilometers =,calc,Miles restart = raw_input(If you would like to perform another conversion type: true\n) -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
Also I'm getting a invalid syntax next to my elif statements that i wasnt getting before. why is this happening now? -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Tuesday, April 9, 2013 9:32:18 AM UTC-4, thomasa...@gmail.com wrote: I'm new to learning python and creating a basic program to convert units of measurement which I will eventually expand upon but im trying to figure out how to loop the entire program. When I insert a while loop it only loops the first 2 lines. Can someone provide a detailed beginner friendly explanation. Here is my program. Also suddenly I'm getting an invalid syntax error next to my elif statements when I wasn't a minute ago. What is wrong here? #!/usr/bin/env python restart = true while restart == true: #Program starts here print To start the Unit Converter please type the number next to the conversion you would like to perform choice = input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) #If user enters 1:Program converts inches to meters if choice == 1: number = int(raw_input(\n\nType the amount in Inches you would like to convert to Meters.\n)) operation = Inches to Meters calc = round(number * .0254, 2) print \n,number,Inches =,calc,Meters restart = raw_input(If you would like to perform another conversion type: true\n #If user enters 2:Program converts millimeters to pints elif choice == 2: number = int(raw_input(\n\nType the amount in Milliliters you would like to convert to Pints.\n)) operation = Milliliters to Pints calc = round(number * 0.0021134,2) print \n,number,Milliliters =,calc,Pints restart = raw_input(If you would like to perform another conversion type: true\n) #If user enter 3:Program converts kilometers to miles elif choice == 3: number = int(raw_input(\n\nType the amount in Kilometers you would like to convert to Miles.\n)) operation = Kilometers to Miles calc = round(number * 0.62137,2) print \n,number,Kilometers =,calc,Miles restart = raw_input(If you would like to perform another conversion type: true\n) -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Tue, Apr 9, 2013 at 11:32 PM, thomasancill...@gmail.com wrote: I'm new to learning python and creating a basic program to convert units of measurement which I will eventually expand upon but im trying to figure out how to loop the entire program. When I insert a while loop it only loops the first 2 lines. Can someone provide a detailed beginner friendly explanation. Here is my program. Hi there! I'm going to make a few general comments about your code; this won't necessarily tell you why it's looping the first two lines (not sure quite what you mean there), but may be of use anyway. Firstly, your code actually doesn't run as-is. It doesn't loop *at all*. Please paste actual runnable code; it makes our job a lot easier! You have a copy-paste problem with one of your input lines (a missing close parenthesis). Once I fixed that, the program appears to loop quite correctly. #!/usr/bin/env python restart = true while restart == true: #Program starts here Putting your comments flush-left as though they were preprocessor directives to an old C compiler is unnecessary; indenting them to the same level as the surrounding code usually makes your code easier to read. print To start the Unit Converter please type the number next to the conversion you would like to perform choice = input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) This is BAD. VERY BAD. As evidenced by the print line, you are using Python 2 (btw, please specify; I tested your code in 2.7, but maybe your version is a bit different); the input() function in Python 2 will eval whatever the user types in. #If user enters 1:Program converts inches to meters if choice == 1: number = int(raw_input(\n\nType the amount in Inches you would like to convert to Meters.\n)) This is a MUCH safer way to accept input. Use raw_input() and then convert it in whatever way is appropriate. operation = Inches to Meters calc = round(number * .0254, 2) print \n,number,Inches =,calc,Meters restart = raw_input(If you would like to perform another conversion type: true\n #If user enters 2:Program converts millimeters to pints elif choice == 2: number = int(raw_input(\n\nType the amount in Milliliters you would like to convert to Pints.\n)) Quite a few of your lines are getting long. That's not a particularly big problem normally (it's a style issue, not a code correctness one), but when you're posting in an email, it's usually safer to shorten the lines to 70-80 characters max; but make sure your code still runs correctly. operation = Milliliters to Pints calc = round(number * 0.0021134,2) print \n,number,Milliliters =,calc,Pints restart = raw_input(If you would like to perform another conversion type: true\n) #If user enter 3:Program converts kilometers to miles elif choice == 3: number = int(raw_input(\n\nType the amount in Kilometers you would like to convert to Miles.\n)) operation = Kilometers to Miles calc = round(number * 0.62137,2) print \n,number,Kilometers =,calc,Miles restart = raw_input(If you would like to perform another conversion type: true\n) There's a lot of duplicated code here, most notably your continuation condition. You can simply back-tab after the elif block and have some code that reunites all the branches; this would also make things clearer. But, as I said, your code seems to work for me (modulo the missing parenthesis). Can you give more details about what's not working, please? ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Tue, Apr 9, 2013 at 11:58 PM, thomasancill...@gmail.com wrote: Also I'm getting a invalid syntax next to my elif statements that i wasnt getting before. why is this happening now? Ah! That's relating to the close parenthesis problem I mentioned. That's the exact issue I saw. When you get told about a problem, sometimes the location pointed out isn't the actual cause. What you have is a (near) guarantee that the problem is no later in the file than that point; often it'll be on that line or the one previous line. In this case, the code is raw_input( elif, which can't be properly parsed - the open parenthesis is forcing the code to be interpreted as an expression, and elif isn't an expression. If you're stuck figuring out a problem, one neat trick is to delete the line of code that's blamed for the problem and try again. If the problem disappears, it was on that line; if the problem moves down to the next line, it's probably on the preceding line. This trick doesn't always work, but it can occasionally be quite handy. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
Sorry I'm just starting to learn python and I'm not sure what version I'm using to be quite honest. I just started typing it up in Komodo edit (Which I'm not personally a fan in particular) I fixed the missing parenthesis which fixed the invalid syntax problem. Also, I apologize for submitting code that did not run. This is the code I have now before I tried looping it again: #!/usr/bin/env python #Program starts here print To start the Unit Converter please type the number next to the conversion you would like to perform choice = raw_input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) #If user enters 1:Program converts inches to meters if choice == 1: #operation = Inches to Meters number = int(raw_input(\n\nType the amount in Inches you would like to convert to Meters.\n)) calc = round(number * .0254, 2) print \n,number,Inches =,calc,Meters restart = raw_input(If you would like to perform another conversion type: true\n) #If user enters 2:Program converts millimeters to pints elif choice == 2: #operation = Milliliters to Pints number = int(raw_input(\n\nType the amount in Milliliters you would like to convert to Pints.\n)) calc = round(number * 0.0021134,2) print \n,number,Milliliters =,calc,Pints restart = raw_input(If you would like to perform another conversion type: true\n) #If user enter 3:Program converts kilometers to miles elif choice == 3: #operation = Kilometers to Miles number = int(raw_input(\n\nType the amount in Kilometers you would like to convert to Miles.\n)) calc = round(number * 0.62137,2) print \n,number,Kilometers =,calc,Miles restart = raw_input(If you would like to perform another conversion type: true\n) Not sure what you meant to exactly by this: There's a lot of duplicated code here, most notably your continuation condition. You can simply back-tab after the elif block and have some code that reunites all the branches; this would also make things clearer Thanks for your reply and if you have any ideas for me to improve my coding that will prevent me from learning python in a sloppy way. I'd like to learn it correctly the first time! -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Tue, Apr 9, 2013 at 11:47 AM, thomasancill...@gmail.com wrote: Sorry I'm just starting to learn python and I'm not sure what version I'm using to be quite honest. I just started typing it up in Komodo edit (Which I'm not personally a fan in particular) I fixed the missing parenthesis which fixed the invalid syntax problem. Also, I apologize for submitting code that did not run. This is the code I have now before I tried looping it again: #!/usr/bin/env python #Program starts here print To start the Unit Converter please type the number next to the conversion you would like to perform choice is not converted to an integer. raw_input returns a string. choice = raw_input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) This will convert choice to an int. Actually, it might not if what you type is not a number. Then it will cause and exception. But for now, do this: choice = int(choice) or leave choices as a string and make your if statements like if choice == '1' #If user enters 1:Program converts inches to meters if choice == 1: #operation = Inches to Meters number = int(raw_input(\n\nType the amount in Inches you would like to convert to Meters.\n)) calc = round(number * .0254, 2) print \n,number,Inches =,calc,Meters restart = raw_input(If you would like to perform another conversion type: true\n) #If user enters 2:Program converts millimeters to pints elif choice == 2: #operation = Milliliters to Pints number = int(raw_input(\n\nType the amount in Milliliters you would like to convert to Pints.\n)) calc = round(number * 0.0021134,2) print \n,number,Milliliters =,calc,Pints restart = raw_input(If you would like to perform another conversion type: true\n) #If user enter 3:Program converts kilometers to miles elif choice == 3: #operation = Kilometers to Miles number = int(raw_input(\n\nType the amount in Kilometers you would like to convert to Miles.\n)) calc = round(number * 0.62137,2) print \n,number,Kilometers =,calc,Miles restart = raw_input(If you would like to perform another conversion type: true\n) Not sure what you meant to exactly by this: There's a lot of duplicated code here, most notably your continuation condition. You can simply back-tab after the elif block and have some code that reunites all the branches; this would also make things clearer Thanks for your reply and if you have any ideas for me to improve my coding that will prevent me from learning python in a sloppy way. I'd like to learn it correctly the first time! -- http://mail.python.org/mailman/listinfo/python-list -- Joel Goldstick http://joelgoldstick.com -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Wed, Apr 10, 2013 at 1:47 AM, thomasancill...@gmail.com wrote: ... I'm not sure what version I'm using ... Try putting these lines into a Python script: import sys print(sys.version) That, on any version of Python (back a fairly long way, Steven D'Aprano can probably say how far), will give you a line or so of output that summarizes your version. For instance, I can get the following: 3.3.0 (v3.3.0:bd8afb90ebf2, Sep 29 2012, 10:55:48) [MSC v.1600 32 bit (Intel)] 2.7.4 (default, Apr 6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)] 3.1.1+ (r311:74480, Nov 2 2009, 14:49:22) [GCC 4.4.1] 3.4.0a0 (default:5dcd7ee0716a, Mar 30 2013, 08:17:06) [GCC 4.7.2] It's a handy system summary. choice = raw_input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) if choice == 1: You probably want to use int(raw_input(...)) here; currently, you're going to get back a string eg 1, which is not equal to the integer 1. But at least now you don't have the automatic evaluation happening :) restart = raw_input(If you would like to perform another conversion type: true\n) Not sure what you meant to exactly by this: There's a lot of duplicated code here, most notably your continuation condition. You can simply back-tab after the elif block and have some code that reunites all the branches; this would also make things clearer Notice how you have the restart = line (which I quote above) duplicated into each of your code branches? That's what I'm talking about. Here's a pseudocode version of the looping you have: while restart: choice = get_choice() if choice == 1: do_choice_1() restart = get_restart() elif choice == 2: do_choice_2() restart = get_restart() elif choice == 3: do_choice_3() restart = get_restart() Here's how you could deduplicate that: while restart: choice = get_choice() if choice == 1: do_choice_1() elif choice == 2: do_choice_2() elif choice == 3: do_choice_3() restart = get_restart() The restart line is unindented one level, which brings it out of the if/elif block, and then it'll get executed regardless of 'choice'. (To strictly match your original code, you'd need to finish the elif block with else: continue, but the code makes at least as good sense without it, so I'd consider that optional.) Thanks for your reply and if you have any ideas for me to improve my coding that will prevent me from learning python in a sloppy way. I'd like to learn it correctly the first time! You're doing fine. The general pattern of programming is: while True: write_code() try: figure_out_what_is_wrong_with_code() except LackOfSkillException: mail(python-list@python.org,smart_question()) run_code() So far, looks like you're following it just fine. :) ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
For system version I get this:
2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)]
Also, I understand what your saying about the continuation code. There's no
need for me to include it in each if/else statement, I could just use it at the
end of the program outside of the statements and it would run no matter what.
But, what I don't understand exactly is the while statement. I've been looking
around a lot lately and notice that people say to use for instance:
while restart: or while true: or while restart = true:
What makes a statement true? Is there a way to return a true or false message.
My method was to ask the user to type true and if that print statement
matched restart = true then the loop would continue but i imagine there is a
better way then matching strings and integers like i have been.
Also what confuses me is that python doesn't use brackets. How do I contain all
of my if/else statements into one while loop? Do I have to indent each line of
code and extra indentation? I'm used to highschool doing c++ and java when I
would just say:
while (x3)
{
if ()
else ()
}
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Re: While loop help
On Tue, Apr 9, 2013 at 12:24 PM, thomasancill...@gmail.com wrote:
For system version I get this:
2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)]
Also, I understand what your saying about the continuation code. There's
no need for me to include it in each if/else statement, I could just use it
at the end of the program outside of the statements and it would run no
matter what. But, what I don't understand exactly is the while statement.
I've been looking around a lot lately and notice that people say to use for
instance:
while restart: or while true: or while restart = true:
What makes a statement true? Is there a way to return a true or false
message. My method was to ask the user to type true and if that print
statement matched restart = true then the loop would continue but i
imagine there is a better way then matching strings and integers like i
have been.
Also what confuses me is that python doesn't use brackets. How do I
contain all of my if/else statements into one while loop? Do I have to
indent each line of code and extra indentation? I'm used to highschool
doing c++ and java when I would just say:
Python uses indentation. Most people set their editor to indent 4 spaces
for each level. It seems odd to people coming from braces languages, but
you get used to it, and it makes code very readable.
As to True/False. There is a boolean type and its values are True and
False (note the capital letter). But other values can be considered
True/False. For instance 0 is considered false, and empty string is
considered false. Any other number is considered true as is any string
that isn't empty. Empty sequences are considered false (Tuples, lists)
while (x3)
{
if ()
else ()
}
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--
Joel Goldstick
http://joelgoldstick.com
--
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Re: While loop help
On Wed, Apr 10, 2013 at 2:24 AM, thomasancill...@gmail.com wrote:
For system version I get this:
2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)]
Lovely! Perfect.
But, what I don't understand exactly is the while statement. I've been
looking around a lot lately and notice that people say to use for instance:
while restart: or while true: or while restart = true:
while x:
y
will check whether x feels trueish, and if it does, will execute y,
then go back and check x again. The general principle is that
something is true and nothing is false - for instance, 0 and 0.0 are
false, while 42 and 0.143 are true. Same goes for lists and such; an
empty list is false, a list with something in it is true.
When you make an actual comparison, you'll get back a result that,
normally, will be one of the strict bool objects True and False. For
instance, the expression:
restart == true
will be True if restart has the string true, and False if it has any
other string.
What makes a statement true? Is there a way to return a true or false
message. My method was to ask the user to type true and if that print
statement matched restart = true then the loop would continue but i imagine
there is a better way then matching strings and integers like i have been.
You can print anything, even the boolean values! :) Try it!
Your method works fine. Since you're getting something with
raw_input(), you're working with strings; whatever the user enters,
that's what you work with. You could make it more friendly by checking
just the first letter and case insensitively, and making it Continue?
Y/N, but that's optional.
Also what confuses me is that python doesn't use brackets. How do I contain
all of my if/else statements into one while loop? Do I have to indent each
line of code and extra indentation? I'm used to highschool doing c++ and java
when I would just say:
while (x3)
{
if ()
else ()
}
It's conventional in C++ to indent every block of code.
int main()
{
//Indent one level
initialize()
while (...)
{
//Indent two levels
do_stuff()
if (...)
{
//Indent three levels
do_more_stuff()
}
do_less_stuff()
}
close_all()
}
Now, just delete all those lines with nothing but braces. You can
still see the program's logical structure:
int main()
//Indent one level
initialize()
while (...)
//Indent two levels
do_stuff()
if (...)
//Indent three levels
do_more_stuff()
do_less_stuff()
close_all()
This is how Python works. (And it's almost legal Python syntax, too.
Add a few colons, fix the comments, pretty much done.) For better or
for worse, Python depends on the indentation; but 99%+ of the time,
you would have that indentation even if it didn't matter. (Personally,
I prefer explicit braces. The duplicated information at times helps
catch bugs, and sometimes I format code according to a logical
structure that doesn't necessarily match its physical structure. It's
a freedom I don't often make use of, but it's one that Python denies
me... as I said, for better or for worse. There are those who argue
that that's a freedom I shouldn't have.)
ChrisA
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Re: While loop help
So what would be the proper way to perform a loop of this program. I still can't quite figure out the best way to do it. -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
I responded before I saw this message, this was very helpful so I appreciate your quick and helpful responses. So do you think prompting for a string and then checking if the string is true is a good practice for something like this? When would checking for true/false be necessary? -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Wed, Apr 10, 2013 at 2:57 AM, thomasancill...@gmail.com wrote: I responded before I saw this message, this was very helpful so I appreciate your quick and helpful responses. So do you think prompting for a string and then checking if the string is true is a good practice for something like this? When would checking for true/false be necessary? Prompting for a string is fairly standard. Just figure out what sort of string you want to look for. Play around with other programs with similar interfaces, and decide what you like. Anything you want to do can be done; most of them won't even be difficult. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 04/09/2013 09:57 AM, thomasancill...@gmail.com wrote: On Tuesday, April 9, 2013 9:32:18 AM UTC-4, thomasa...@gmail.com wrote: I'm new to learning python and creating a basic program to convert units of measurement which I will eventually expand upon but im trying to figure out how to loop the entire program. When I insert a while loop it only loops the first 2 lines. Can someone provide a detailed beginner friendly explanation. Here is my program. Also suddenly I'm getting an invalid syntax error next to my elif statements when I wasn't a minute ago. What is wrong here? #!/usr/bin/env python restart = true while restart == true: #Program starts here print To start the Unit Converter please type the number next to the conversion you would like to perform choice = input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to Square-Miles\n) Quoting that many lines, and double-spacing every one of them is very impolite. Almost makes me want to skip the thread. If you must use buggy googlegroups, then at least fix its most annoying bugs: read this http://wiki.python.org/moin/GoogleGroupsPython. (rest deleted, as the point has been made) -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
sorry i just started using google groups, not really all that sure how to use it properly. -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Wed, Apr 10, 2013 at 3:18 AM, thomasancill...@gmail.com wrote: sorry i just started using google groups, not really all that sure how to use it properly. The best way to use Google Groups is to not use it, frankly. Just subscribe to the mailing list in gmail; it has its own issues (eg it encourages top-posting by putting a couple of blank lines at the top of the quoted text), but they're easier to work around than the GG problems. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 04/09/2013 12:57 PM, thomasancill...@gmail.com wrote: I responded before I saw this message, this was very helpful so I appreciate your quick and helpful responses. So do you think prompting for a string and then checking if the string is true is a good practice for something like this? When would checking for true/false be necessary? No, DON'T check for the string to be true, check if it matches the requirements. Word the question for the user's convenience, not the programming language's. Don't ask for true and false, ask Continue? and accept Y or N. Or ask Q for quit. Or whatever. Make your comparison case-insensitive, and permit one-character responses. continue = y while continue[:1].lower() == y: do some work continue = raw_input(Do you want to continue (y/n)? -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 04/09/2013 01:18 PM, thomasancill...@gmail.com wrote: sorry i just started using google groups, not really all that sure how to use it properly. IMHO, best way is to switch to a good email program, and mail your messages to comp.lang.python. That's after subscribing via http://mail.python.org/mailman/listinfo/python-list You can set up filters in your email program so all forum messages to into a separate folder, one per forum. And you tell your email program to use text mail, not html. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 9 avr, 15:32, thomasancill...@gmail.com wrote:
I'm new to learning python and creating a basic program to convert units of
measurement which I will eventually expand upon but im trying to figure out
how to loop the entire program. When I insert a while loop it only loops the
first 2 lines. Can someone provide a detailed beginner friendly explanation.
Here is my program.
#!/usr/bin/env python
restart = true
while restart == true:
#Program starts here
print To start the Unit Converter please type the number next to the
conversion you would like to perform
choice = input(\n1:Inches to Meter\n2:Millileters to Pint\n3:Acres to
Square-Miles\n)
#If user enters 1:Program converts inches to meters
if choice == 1:
number = int(raw_input(\n\nType the amount in Inches you would like
to convert to Meters.\n))
operation = Inches to Meters
calc = round(number * .0254, 2)
print \n,number,Inches =,calc,Meters
restart = raw_input(If you would like to perform another conversion
type: true\n
#If user enters 2:Program converts millimeters to pints
elif choice == 2:
number = int(raw_input(\n\nType the amount in Milliliters you would
like to convert to Pints.\n))
operation = Milliliters to Pints
calc = round(number * 0.0021134,2)
print \n,number,Milliliters =,calc,Pints
restart = raw_input(If you would like to perform another conversion
type: true\n)
#If user enter 3:Program converts kilometers to miles
elif choice == 3:
number = int(raw_input(\n\nType the amount in Kilometers you would
like to convert to Miles.\n))
operation = Kilometers to Miles
calc = round(number * 0.62137,2)
print \n,number,Kilometers =,calc,Miles
restart = raw_input(If you would like to perform another conversion
type: true\n)
-
More (very) important:
meter: lower case m
kilometre: lower case k
milli: lower case m
http://www.bipm.org/en/home/
Less important:
Start with something simple and increase the complexity eg:
# Py 3.2
while True:
... s = input('km: ')
... if s == 'q':
... break
... a = float(s)
... print('{} [kilometre] == {} [metre]'.format(a, a * 1000))
...
km: 1
1.0 [kilometre] == 1000.0 [metre]
km: 1.3456
1.3456 [kilometre] == 1345.6 [metre]
km: q
jmf
--
http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Wed, 10 Apr 2013 02:10:29 +1000, Chris Angelico wrote: On Wed, Apr 10, 2013 at 1:47 AM, thomasancill...@gmail.com wrote: ... I'm not sure what version I'm using ... Try putting these lines into a Python script: import sys print(sys.version) That works (of course), but in every Python version I've seen, one merely needs to invoke the python interactive interpreter and the banner is displayed: $ python Python 2.7.3 (default, Aug 9 2012, 17:23:57) [GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2 Type help, copyright, credits or license for more information. quit() $ -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On 04/09/2013 03:35 PM, Walter Hurry wrote: On Wed, 10 Apr 2013 02:10:29 +1000, Chris Angelico wrote: On Wed, Apr 10, 2013 at 1:47 AM, thomasancill...@gmail.com wrote: ... I'm not sure what version I'm using ... Try putting these lines into a Python script: import sys print(sys.version) That works (of course), but in every Python version I've seen, one merely needs to invoke the python interactive interpreter and the banner is displayed: $ python Python 2.7.3 (default, Aug 9 2012, 17:23:57) [GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2 Type help, copyright, credits or license for more information. quit() $ And if several are installed, that isn't necessarily the one that'll run when one runs a script. Depends on how the script is invoked (and on what OS is running), and on the shebang line, PATH, etc. The real point about those two lines is that they can be added to most scripts. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Tue, 09 Apr 2013 16:12:34 -0400, Dave Angel wrote: On 04/09/2013 03:35 PM, Walter Hurry wrote: On Wed, 10 Apr 2013 02:10:29 +1000, Chris Angelico wrote: On Wed, Apr 10, 2013 at 1:47 AM, thomasancill...@gmail.com wrote: ... I'm not sure what version I'm using ... Try putting these lines into a Python script: import sys print(sys.version) That works (of course), but in every Python version I've seen, one merely needs to invoke the python interactive interpreter and the banner is displayed: $ python Python 2.7.3 (default, Aug 9 2012, 17:23:57) [GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2 Type help, copyright, credits or license for more information. quit() $ And if several are installed, that isn't necessarily the one that'll run when one runs a script. Depends on how the script is invoked (and on what OS is running), and on the shebang line, PATH, etc. The real point about those two lines is that they can be added to most scripts. Well yes, but if multiple versions are installed and the script has a shebang, then invoking the same interpreter as the shebang does will produce the same result. But this is dancing on the head of a pin anyway; OP just didn't know what version of Python he was running, so he is extremely unlikely to have more than one version installed, and to be choosing amongst them. -- http://mail.python.org/mailman/listinfo/python-list
Re: While loop help
On Wed, Apr 10, 2013 at 6:59 AM, Walter Hurry walterhu...@lavabit.com wrote: On Tue, 09 Apr 2013 16:12:34 -0400, Dave Angel wrote: On 04/09/2013 03:35 PM, Walter Hurry wrote: On Wed, 10 Apr 2013 02:10:29 +1000, Chris Angelico wrote: On Wed, Apr 10, 2013 at 1:47 AM, thomasancill...@gmail.com wrote: ... I'm not sure what version I'm using ... Try putting these lines into a Python script: import sys print(sys.version) That works (of course), but in every Python version I've seen, one merely needs to invoke the python interactive interpreter and the banner is displayed: $ python Python 2.7.3 (default, Aug 9 2012, 17:23:57) [GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2 Type help, copyright, credits or license for more information. quit() $ And if several are installed, that isn't necessarily the one that'll run when one runs a script. Depends on how the script is invoked (and on what OS is running), and on the shebang line, PATH, etc. The real point about those two lines is that they can be added to most scripts. Well yes, but if multiple versions are installed and the script has a shebang, then invoking the same interpreter as the shebang does will produce the same result. I still went with a guaranteed-safe option. Adding those two lines to his script is sure to report on the Python being used to run the script, and it's not as if it's a massively-complex incantation :) But this is dancing on the head of a pin anyway; OP just didn't know what version of Python he was running, so he is extremely unlikely to have more than one version installed, and to be choosing amongst them. Dunno about that. It's pretty easy to have two versions of something without understanding why. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
