> Message: 3 > Date: Tue, 10 Sep 2013 09:58:31 +0200 > From: Thabile Rampa <thabilera...@gmail.com> > To: tutor@python.org > Subject: [Tutor] [Re:] I need help with the following question > Message-ID: > <caoiosuxureh2o2wbnvyhchcyc7iz64ibwqavygzbuoso4mx...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > On Aug 27, 2013, at 3:40 AM, isaac Eric wrote > > <snip> > > print "For a circle of radius %s the area is %s" % (radius,area) > <snip>> Question: What is the purpose of %s ? > > I will admit that this is homework for me. However, this is more for my log > book and not for marks. > > According to my understanding, the purpose of the %s is to turn the numbers, > which the program has recognized as numbers, into strings, so that they fit > in the print command without any syntax errors. > > Could you guide me in the right direction if it is completely off? > > *Tab Tab*
I'm not a python "brainiac" so I apologize in advance if my answer is lacking I'll try to be as thorough as possible. In the light of another recent question on here "Where do I start python" I want to point out there's been tons of linkage to places where it's rather easy to find the answer what %s %d and %r are.... One of my favs is the http://learnpythonthehardway.org/book/ and if you start from exercise 5 onwards you should get a better idea of all the print options there are in Python and how to use them efficiently. If you were inquiring SPECIFICALLY about 'formaters' (the %s,d,i,r.... look no further then basic Python manual here: http://docs.python.org/2/library/stdtypes.html#string-formatting Lucky for you the %s automatically converts any argument to string with str() which works for everything in Python, except you might not like the look of the output. Be careful to use %i or %d for integers otherwise floats will be rounded up. Printing strings when using %i will report an error. I don't think there's any difference between %d (d does NOT stand for double) and %i. If you want pretty decimals (1.1) and not floats (1.100000001) use the decimal module. Else if you were interested in all the ways you can print in python just look at the learn python link but here's the crash course anyhow. I don't think you should have any problems if you ever worked in any of the big c's before. Printing in Python 3 onwards needs parentheses around the arguments you're printing, I think for Python <3 following should work: Basically if in python you want to print string, python can automatically connect them in a sentence: >>>> print "This"+"is"+"ok" This is ok but that won't work if the print arguments are not strings i.e.: >>>> print "This"+"is"+"not" + 6 + "ok" TypeError: cannot concatenate string and integer objects and it's also silly to do that, could you imagine explicitly converting everything to string? >>>> print str(hours)+":"+str(minutes)+":"+str(seconds)) fugly! What you want to do, resembles the c and c++ printf syntax >>>>print "You can add string %s and number %d like this" %(string, number) You can add string Banana and number 5 like this Or also fine, valid only for python>=2.6, and also the way that I prefer for longer strings is the C# syntax (I think): >>>>print "Something is here: {0}".format(anything) Something is here: (any number or string) Because it avoids the necessity for declaring exactly what is it you're printing and program won't crash, or at least it avoids the need to add special try catch blocks just for printing. If you see your output is not what you want you can return and try to work out exactly what happened. Hope no serious rules were broken by answering to this question... Regards, Dino _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
