Python Tutorial

Python Tutorial

Release 2.6.4

Guido van Rossum  

Fred L. Drake, Jr., editor

November 25, 2009

Python Software Foundation

Email: docs@python.org

CONTENTS

1 Whetting Your Appetite 3

2 Using the Python Interpreter 5

2.1 InvokingtheInterpreter ....................................... 5

2.2 TheInterpreterandItsEnvironment ................................. 6

3 An Informal Introduction to Python 9

3.1 UsingPythonasaCalculator .................................... 9

3.2 FirstStepsTowardsProgramming .................................. 17

4 More Control Flow Tools 19

4.1 ifStatements ............................................ 19

4.2 forStatements ........................................... 19

4.3 The range()Function....................................... 20

4.4 breakand continueStatements, and elseClausesonLoops ................. 20

4.5 passStatements........................................... 21

4.6 DefiningFunctions .......................................... 21

4.7 MoreonDefiningFunctions ..................................... 23

4.8 Intermezzo:CodingStyle ...................................... 26

5 Data Structures 29

5.1 MoreonLists ............................................. 29

5.2 The delstatement.......................................... 33

5.3 TuplesandSequences ........................................ 33

5.4 Sets.................................................. 34

5.5 Dictionaries.............................................. 35

5.6 LoopingTechniques ......................................... 35

5.7 MoreonConditions ......................................... 36

5.8 ComparingSequencesandOtherTypes ............................... 37

6 Modules 39

6.1 MoreonModules .......................................... 40

6.2 StandardModules .......................................... 42

6.3 The dir()Function......................................... 42

6.4 Packages ............................................... 43

7 Input and Output 47

7.1 FancierOutputFormatting ...................................... 47

7.2 ReadingandWritingFiles ...................................... 50

8 Errors and Exceptions 53

8.1 SyntaxErrors ............................................. 53

8.2 Exceptions .............................................. 53

8.3 HandlingExceptions ......................................... 54

8.4 RaisingExceptions .......................................... 55

8.5 User-definedExceptions ....................................... 56

8.6 DefiningClean-upActions ...................................... 57

8.7 PredefinedClean-upActions ..................................... 58

9 Classes 59

9.1 AWordAboutNamesandObjects ................................. 59

9.2 PythonScopesandNamespaces ................................... 59

9.3 AFirstLookatClasses ........................................ 61

9.4 RandomRemarks .......................................... 63

9.5 Inheritance .............................................. 64

9.6 PrivateVariables ........................................... 65

9.7 OddsandEnds ............................................ 66

9.8 ExceptionsAreClassesToo ..................................... 66

9.9 Iterators................................................ 67

9.10 Generators .............................................. 68

9.11 GeneratorExpressions ........................................ 68

10 Brief Tour of the Standard Library 71

10.1 OperatingSystemInterface ..................................... 71

10.2 FileWildcards ............................................ 71

10.3 CommandLineArguments ..................................... 71

10.4 ErrorOutputRedirectionandProgramTermination . . . . . . . . . . . . . . . . . . . . . . . . . 72

10.5 StringPatternMatching ....................................... 72

10.6 Mathematics ............................................. 72

10.7 InternetAccess ............................................ 73

10.8 DatesandTimes ........................................... 73

10.9 DataCompression .......................................... 73

10.10PerformanceMeasurement ...................................... 74

10.11QualityControl ............................................ 74