1、Python Tutorial Pythona92a128a141a72Release 2.5b2Guido van RossumFred L. Drake, Jr., editor11th July, 2006Python Software FoundationEmail: docspython.orgCopyright 2001-2006 Python Software Foundation. All rights reserved.Copyright 2000 BeO. All rights reserved.Copyright 1995-2000 Corporation for Nat
2、ional Research Initiatives. All rights reserved.Copyright 1991-1995 Stichting Mathematisch Centrum. All rights reserved.See the end of this document for complete license and permissions information.AbstractPython is an easy to learn, powerful programming language. It has efficient high-level data st
3、ructures and a simplebut effective approach to object-oriented programming. Pythons elegant syntax and dynamic typing, together with itsinterpreted nature, make it an ideal language for scripting and rapid application development in many areas on mostplatforms.Pythona180a152a171a78a180a198a83a27a114
4、a140a27a63a167a138a243a34a167a157a185a10a112a8a27a112a63a234a226a40a8a167a85a10a94a123a252a13a112a8a27a144a170a63a49a161a149a233a150a63a167a34Pythona96a228a27a138a123a218a196a21a97a46a167a177a57a167a85a44a27a41a186a85a229a167a166a217a164a143a10a140a245a234a178a17a254a50a141a183a94a117a136a43a141a27a
5、110a142a12a29a138a243a218a109a117a130a184a34The Python interpreter and the extensive standard library are freely available in source or binary form for all majorplatforms from the Python Web site, http:/www.python.org/, and may be freely distributed. The same sitealso contains distributions of and p
6、ointers to many free third party Python modules, programs and tools, and additionaldocumentation.Pythona41a186a236a57a217a42a208a73a79a165a27a13a232a218a63a200a135a29a140a177a108Pythona27Weba213a58,http:/www.python.org/,a57a217a164a107a186a148a213a254a157a164a188a26a167a191a133a140a177a103a100a117a2
7、17a34a84a213a58a254a143a74a248a10Python a27a152a10a49a110a144a28a172a167a167a83a167a243a228a167a177a57a78a92a27a169a12a34The Python interpreter is easily extended with new functions and data types implemented in C or C+ (or otherlanguages callable from C). Python is also suitable as an extension lan
8、guage for customizable applications.Pythona41a186a236a140a177a233a78a180a27a207a76Ca189a246C+a163a189a246a217a167a140a177a207a76Ca78a94a27a138a243a164a42a208a35a188a234a218a234a226a97a46a34Pythona143a140a177a138a143a189a155a65a94a27a42a208a138a243a34This tutorial introduces the reader informally to
9、the basic concepts and features of the Python language and system. Ithelps to have a Python interpreter handy for hands-on experience, but all examples are self-contained, so the tutorialcan be read off-line as well.a29a195a254a149a214a246a48a11Pythona138a243a57a217a88a218a27a196a29a127a163a134a86a1
10、03a34a27a220Pythona41a186a236a198a83a172a233a107a144a207a167a216a76a164a107a27a126a102a209a174a157a41a51a169a165a167a164a177a249a29a195a254a143a233a140a177a108a130a29a214a34For a description of standard objects and modules, see the Python Library Reference document. The Python Refer-ence Manual give
11、s a more formal definition of the language. To write extensions in C or C+, read Extending andEmbedding the Python Interpreter and Python/C API Reference. There are also several books covering Python indepth.a73a135a107a39a73a79a233a150a218a28a172a27a141a91a48a11a27a123a167a158a6a206Pythona165a235a1
12、27a195a254a169a12a34Pythona235a127a195a254a74a248a10a141a245a27a39a117a138a243a144a161a27a20a170a96a178a34a73a135a63a21Ca189C+a42a208a167a158a29a214Pythona41a186a236a27a42a208a218a56a164a177a57Python/C APIa235a127a195a254a34a249a65a29a214a186a88a10a136a135a29a221a254a27Pythona127a163a34This tutorial
13、 does not attempt to be comprehensive and cover every single feature, or even every commonly usedfeature. Instead, it introduces many of Pythons most noteworthy features, and will give you a good idea of thelanguages flavor and style. After reading it, you will be able to read and write Python modul
14、es and programs, and youwill be ready to learn more about the various Python library modules described in the Python Library Reference.a29a195a254a216a172a186a88Pythona27a164a107a245a85a167a143a216a172a22a41a186a164a94a20a27a164a107a131a39a27a127a163a34a131a135a167a167a48a11a10a78a245Pythona165a129a
15、218a60a53a56a27a245a85a167a249a172a233a214a246a221a186a249a128a138a243a27a186a130a140a107a144a207a34a214a76a167a0a167a92a65a84a140a177a29a214a218a63a21Pythona28a172a218a167a83a167a26a101a53a140a177a108Pythona165a235a127a195a254a165a63a152a218a198a83Pythona69a44a245a67a27a165a218a28a172a34CONTENTS1 W
16、hetting Your Appetitea109a157a232 12 Using the Python Interpretera166a94Pythona41a186a236 52.1 Invoking the Interpretera78a94a41a186a236 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.2 The Interpreter and Its Environmenta41a186a236a57a217a130a184 . . . . . . . . . . . . . .
17、. . . . . . . . . . . 73 More Control Flow Toolsa29a92a54a167a155a155 113.1 if Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2 for Statements fora138a233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.3
18、 The range() Function range()a188a234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4 break and continue Statements, and else Clauses on Loops breaka218continuea138a233,a177a57a204a130a165a27elsea102a233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . 133.5 pass Statements passa138a233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.6 Defining Functionsa189a194a188a234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.7 More on Defining Functionsa29a92a188a234a189a194. . . .
20、. . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Data Structuresa234a226a226a40a40a8 234.1 More on Listsa29a92a243a76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.2 The del statement dela138a233 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、 . . . . . . . . . . 284.3 Tuples and Sequencesa3a124a218a83a15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284.4 Setsa56a220 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.5 Dictionariesa105a59. . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.6 Looping Techniquesa204a130a69a226 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.7 More on Conditionsa29a92a94a135a155a155 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.8
23、 Comparing Sequences and Other Typesa216a211a83a15a97a46a27a39a22 . . . . . . . . . . . . . . . . . . . . . 345 Modulesa28a172 375.1 More on Modulesa29a92a28a172 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385.2 Standard Modulesa73a79a28a172 . . . . . . . . . . . .
24、. . . . . . . . . . . . . . . . . . . . . . . . . . . 415.3 The dir() Function dir()a188a234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.4 Packagesa157 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 Input and Outputa209
25、a92a218a209a209 496.1 Fancier Output Formattinga23a79a209a209a130a170 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496.2 Reading and Writing Filesa214a21a169a135 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537 Errors and Exceptionsa134a216a218a201a126 577.1 S
26、yntax Errorsa138a123a134a216 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.2 Exceptionsa201a126 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.3 Handling Exceptionsa63a110a201a126 . . . . . . . . . . . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . 58i7.4 Raising Exceptionsa14a209a201a126 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 617.5 User-defined Exceptionsa94a114a103a189a194a201a126 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627.6 Defining Clean-up
28、 Actionsa189a194a152a110a49a143 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637.7 Predefined Clean-up Actionsa253a189a194a152a110a49a143 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 658 Classes 678.1 A Word About Terminologya226a138a251a33 . . . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . 678.2 Python Scopes and Name Spacesa138a94a141a218a183a182a152a109 . . . . . . . . . . . . . . . . . . . . . . . . . 688.3 A First Look at Classesa208a163a97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708.4 Random Remarksa152a10a96a
30、178 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748.5 Inheritancea85a171 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 768.6 Private Variablesa104a107a67a254 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31、. . . . . . . 778.7 Odds and Endsa214a191 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 788.8 Exceptions Are Classes Tooa201a126a143a180a97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 798.9 Iteratorsa83a147a236 . . . . . . . . . . . . . . .
32、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 808.10 Generatorsa41a164a236 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 818.11 Generator Expressionsa41a164a236a76a136a170. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 829
33、Brief Tour of the Standard Librarya73a79a165a86a65 839.1 Operating System Interfacea246a138a88a218a26a157 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839.2 File Wildcardsa169a135a207a27a206 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 849.3 Command
34、Line Argumentsa183a45a49a235a234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 849.4 Error Output Redirection and Program Terminationa134a216a209a209a173a189a149a218a167a83a170a142 . . . . . . . . . . 849.5 String Pattern Matchinga105a206a71a20a75a154a27. . . . . . . . . . . . . .
35、. . . . . . . . . . . . . . . . . . 859.6 Mathematicsa234a198 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 859.7 Internet Accessa112a233a31a150a175 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.8 Dates and Timesa70a207a21
36、8a158a109 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.9 Data Compressiona234a226a216a160 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 879.10 Performance Measurementa53a85a221a254 . . . . . . . . . . . . . . . . . . . . . . . . . . .
37、. . . . . . . 879.11 Quality Controla159a254a155a155 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 879.12 Batteries Included . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8810 Brief Tour of the Standard Library Part IIa73a79
38、a165a86a65 9110.1 Output Formattinga130a170a122a209a209 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9110.2 Templatinga28a135 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9210.3 Working with Binary Data Record Layoutsa166a94a1
39、9a63a155a80a185a0 . . . . . . . . . . . . . . . . . . . . 9310.4 Multi-threadinga245a130a167 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9410.5 Logginga70a147. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9510.6 Wea
40、k Referencesa102a218a94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9510.7 Tools for Working with Listsa243a76a243a228 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9610.8 Decimal Floating Point Arithmetica155a63a155a50a58a234a142a123 . . . . .
41、 . . . . . . . . . . . . . . . . . . . 9811 What Now? 99A Interactive Input Editing and History Substitution 101A.1 Line Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101A.2 History Substitution . . . . . . . . . . . . . . . . . . . . . . . . .
42、 . . . . . . . . . . . . . . . . . . 101A.3 Key Bindings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101A.4 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103B Floating Point Arithmetic: Issues
43、and Limitations 105B.1 Representation Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107C History and License 109C.1 History of the software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109iiC.2 Terms and conditions
44、for accessing or otherwise using Python . . . . . . . . . . . . . . . . . . . . . 110C.3 Licenses and Acknowledgements for Incorporated Software . . . . . . . . . . . . . . . . . . . . . . 113D Glossary 123Index 127iiiivCHAPTERONEWhetting Your Appetitea109a157a232If you do much work on computers, ev
45、entually you find that theres some task youd like to automate. For example,you may wish to perform a search-and-replace over a large number of text files, or rename and rearrange a bunch ofphotofilesinacomplicatedway. Perhapsyoudliketowriteasmallcustomdatabase, oraspecializedGUIapplication,or a simp
46、le game.a98a23a88a74a92a135a94a79a142a197a137a233a245a243a138a167a92a70a34a107a10a63a214a140a177a103a196a17a164a34a126a88a167a92a140a85a70a34a51a140a254a27a169a29a169a135a165a63a49a6a233a79a134a246a138a167a143a78a180a207a76a69a44a27a144a170a173a183a182a191a173a35a123a152a152a49a227a148a169a135a34a14
47、0a85a92a85a129a21a135a2a27a189a155a234a226a165a167a189a246a65a207a27GUIa65a94a167a83a167a189a246a123a252a27a105a90a34If youre a professional software developer, you may have to work with several C/C+/Java libraries but find the usualwrite/compile/test/re-compile cycle is too slow. Perhaps youre writ
48、ing a test suite for such a library and find writingthe testing code a tedious task. Or maybe youve written a program that could use an extension language, and youdont want to design and implement a whole new language for your application.a88a74a92a180a135a59a146a27a94a135a109a117a246a167a92a140a85a
49、135a94a65a135C/C+/Javaa165a243a138a167a2a180a117a121a207a126a27a63a21/a63a200/a255a193/a173a63a200a204a130a20a250a10a34a140a85a92a51a137a122a135a165a63a21a233a65a27a255a193a147a232a167a2a180a117a121a249a180a152a135a134a60a27a185a14a34a189a246a92a51a63a21a152a135a145a107a42a208a138a243a27a167a83a167a13a92a216a142a137a92a27a65a94a167a83a23a79a218a162a121a152a128a28a35a27a138a243a34Python is just the language for you.Pythona210a180a92a73a135a27a138a243a34You could write a UNIX shell script or Windows batch files for some of these tasks, but shell scripts are be
