Think Python - Denison University

5.11. Keyboard input 455.11 KeyboardinputThe programs we have written so far are a bit rude in the sense that they accept no input from theuser. They justdo the samething every time.Pythonprovidesabuilt-infunctioncalledraw_inputthatgetsinputfromthekeyboard 1 . Whenthisfunctioniscalled,theprogramstopsandwaitsfortheusertotypesomething. WhentheuserpressesReturnor Enter, theprogram resumes andraw_inputreturns what theuser typed as astring.>>> input = raw_input()What are you waiting for?>>> print inputWhat are you waiting for?Before getting input from the user, it is a good idea to print a prompt telling the user what to input.raw_inputcan take aprompt asan argument:>>> name = raw_input('What...is your name?\n')What...is your name?Arthur, King of the Britons!>>> print nameArthur, King of the Britons!The sequence \n at the end of the prompt represents a newline, which is a special character thatcauses alinebreak. That’s why the user’sinput appears below the prompt.Ifyou expect the user totype aninteger, you can trytoconvert the returnvalue toint:>>> prompt = 'What...is the airspeed velocity of an unladen swallow?\n'>>> speed = raw_input(prompt)What...is the airspeed velocity of an unladen swallow?17>>> int(speed)17But ifthe user types something other than astringofdigits, you get an error:>>> speed = raw_input(prompt)What...is the airspeed velocity of an unladen swallow?What do you mean, an African or a European swallow?>>> int(speed)ValueError: invalid literal for int()We willseehow tohandle thiskind of error later.5.12 DebuggingThe traceback Python displays when an error occurs contains a lot of information, but it can beoverwhelming, especially when there are many frames on the stack. The most useful parts areusually:1 InPython3.0, this functionis namedinput.