python核心编程第二版附录a

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1、Chun_AppA.fmPage1011Wednesday,August23,20065:19PMAnswerstoSelectedExercisesChapter25.Loopsandnumbersa)i=0whilei<11:i+=1b)foriinrange(11):pass6.Conditionalsn=int(raw_input('enteranumber:'))ifn<0:print'negative'elifn>0:print'positive'else:print'zero'1011Chun_AppA.fmPage1012Wednesday,August23,2006

2、5:19PM1012AppendixA7.Loopsandstringss=raw_input('enterastring:')foreachCharins:printeachChar#(doesnotprintindex)orforiinrange(len(s)):printi,s[i]ori=0slen=len(s)whilei

3、)printsubtotor#usessum()BIFandgeneratorexpressionsprintsum(int(raw_input('enteranumber:'))foriinrange(5))Chapter34.StatementsUse;5.StatementsUse(unlesspartofacomma-separatedsequenceinwhichcaseisoptional)7.Identifiers40XLnumber$saving$symbolprintkeyword0x40Lnumberbig-daddysymbol2hot2touchnumber

4、thisIsn'tAVarsymbolifkeywordcounter-1symbolChun_AppA.fmPage1013Wednesday,August23,20065:19PMAnswerstoSelectedExercises1013Chapter41.PythonobjectsAllPythonobjectshavethreeattributes:type,ID,andvalue.Allareread-onlywithapossibleexceptionofthevalue(whichcanbechangedonlyiftheobjectismutable).5.str(

5、)vs.repr()repr()isabuilt-infunctionwhilestr()wasabuilt-infunctionthatchangedtoafactoryfunctioninPython2.2.Theywillbothreturnastringrep-resentationofanobject;however,str()returnsaprintablestringrepresenta-tionwhilerepr()(andthebackquoteoperator‘‘)returnanevaluatablestringrepresentationofanobject

6、,meaningthatitisastringthatrepresentsa(valid)Pythonobjectthatwouldbecreatedifpassedtoeval().6.Objectequalitytype(a)==type(b)whetherthevalueoftype(a)isthesameasthevalueoftype(b)...==isavaluecomparetype(a)istype(b)whetherthetypeobjectsreturnedbytype(a)andtype(b)arethesameobjectSincethereexistsonl

7、yone(type)objectforeachbuilt-intype,thereisnoneedtochecktheirvalues;hence,onlythelatterformshouldbeused.Chapter58.Geometryimportmathdefsqcube():s=float(raw_input('enterlengthofoneside:'))print'theareais:',s**2.,'(unitssquared)'pri