《Python语言程序设计》课件-第五章（中英文课件）

Python语言程序设计【字符串的写法】PythonLanguageProgramming[Stringwriting]在Python中字符串可以用单引号（''）和双引号（""）标识，对于跨行的字符串可以用“三引号”（三个单引号'''或三个双引号"""）标识。知识点【字符串的写法】12str1='HelloWorld!'

str2="Derisweng"【例】用单引号（''）和双引号（""）创建字符串12345str3="""

这是一个多行字符串的例子

使用制表符TAB(\t)，也可以使用换行符\n

进行换行

"""

print(str3)【例】用三引号创建字符串这是一个多行字符串的例子使用制表符TAB( )，也可以使用换行符进行换行输出结果：InPython,stringscanbeidentifiedwithsinglequotationmarks('')anddoublequotationmarks(""),andcrosslinestringscanbeidentifiedwith"threequotationmarks"(threesinglequotationmarks''orthreedoublequotationmarks"").KnowledgePoints[Stringwriting]12str1='HelloWorld!'

str2="Derisweng"[Example]Creatingstringswithsinglequotes('')anddoublequotes("")12345str3="""

Thisisanexampleofamulti-linestring

UsetabTAB(t),orusenewlinenfornewline

"""

print(str3)[Example]CreatingastringwithtriplequotesThisisanexampleofamulti-linestringthatUseTabTAB（ ),youcanalsouselinebreaks

PerformlinefeedsOutputresult:三引号具有所见即所得的效果，其典型的应用场景就是当你需要一段HTML或者SQL语句时，如果用字符串组合或者特殊字符串转义，将会非常麻烦，而使用三引号就非常方便。知识点【字符串的写法】123456789strHTML="""

<divclass="title-box">

<h2class="title-blog">

<ahref="https://www.P">Python</a>

</h2>

<pclass="description">春江花月夜</p>

</div>

"""

print(strHTML)【例】三引号应用在HTML的定义中<divclass="title-box"><h2class="title-blog"><ahref="https://www.P">Python</a></h2><pclass="description">春江花月夜</p></div>输出结果：Threequotationmarkshavetheeffectofwhatyouseeiswhatyouget.ItstypicalapplicationscenarioisthatwhenyouneedanHTMLorSQLstatement,itwillbeverytroublesometousestringcombinationsorspecialstringstoescape.Itisveryconvenienttousethreequotationmarks.123456789strHTML="""

<divclass="title-box">

<h2class="title-blog">

<ahref="https://www.P">Python</a>

</h2>

<pclass="description">MoonlightonSpringRiver</p>

</div>

"""

print(strHTML)[Example]ThreequotationmarksareusedinthedefinitionofHTML<divclass="title-box"><h2class="title-blog"><ahref="https://www.P">Python</a></h2><pclass="description">MoonlightonSpringRiver</p></div>Outputresult:KnowledgePoints[Stringwriting]Python语言程序设计【字符串操作】PythonLanguageProgramming[Stringmanipulation]知识点【字符串操作】-1.求字符串长度12str1='HelloWorld!'

print("str1的长度:",len(str1))【例】len()函数应用str1的长度:12输出结果：KnowledgePoints[Stringmanipulation]-1.Findthelengthofthestring12str1='HelloWorld!'

print("str1length:",len(str1))[Example]Applicationoflen()functionLengthofstr1:12Outputresult:知识点【字符串操作】-2.访问字符串中的值1234str1='HelloWorld!'

str2="Python"

print("str1[0]:",str1[0])

print("str2[1:5]:",str2[1:5])【例】用方括号[]来访问子字符串str1[0]:Hstr2[1:5]:unoo输出结果：[Stringmanipulation]-2.accessingthevalueinastring1234str1='HelloWorld!'

str2="Python"

print("str1[0]:",str1[0])

print("str2[1:5]:",str2[1:5])[Example]Usingsquarebrackets[]toaccesssubstrings,thestr1[0]:Hstr2[1:5]:unooKnowledgePointsOutputresult:知识点【字符串操作】-3.字符串截取与拼接12str1='HelloWorld!'

print("更新后字符串:",str1[:6]+'Weng!')【例】字符串截取与拼接更新后字符串:HelloWeng!输出结果：[Stringmanipulation]-3.Stringtruncationandsplicing12str1='HelloWorld!'

print("Updatedstring:",str1[:6]+'Weng!')[Example]StringinterceptionandsplicingUpdatedstring:HelloWeng!KnowledgePointsOutputresult:知识点【字符串操作】-4.字符串替换1print('AACBBBCAA'.replace('BBB','AAA'))【例】字符串替换AACAAACAA输出结果：[Stringmanipulation]-4.Stringsubstitution1print('AACBBBCAA'.replace('BBB','AAA'))[Example]StringReplacementAACAAACAAKnowledgePointsOutputresult:知识点【字符串操作】-5.在字符串中查找子串并返回子串的起始位置1print("DerisWeng".find("Weng"))【例】在字符串中查找子串5输出结果：[Stringmanipulation]-5.Findingasubstringinastringandreturningthestartingpositionofthesubstring1print("DerisWeng".find("Weng"))[Example]Findingasubstringinastring5KnowledgePointsOutputresult:知识点【字符串操作】-6.大小写转换1234strU="DerisWeng".upper()

print(strU)

strL=strU.lower()

print(strL)【例】字符串大小写转换DERISWENGderisweng输出结果：[Stringmanipulation]-6.caseconversion1234strU="DerisWeng".upper()

print(strU)

strL=strU.lower()

print(strL)[Example]StringcaseconversionDERISWENGderiswengKnowledgePointsOutputresult:知识点【字符串操作】-7.去空格123print("Hello,Deris,Weng".strip())

print("Hello,Deris,Weng".lstrip())

print("Hello,Deris,Weng".rstrip())【例】去空格Hello,Deris,WengHello,Deris,WengHello,Deris,Weng输出结果：去掉两边去掉左边去掉右边[Stringmanipulation]-7.De-space123print("Hello,Deris,Weng".strip())

print("Hello,Deris,Weng".lstrip())

print("Hello,Deris,Weng".rstrip())[Example]RemovethespaceHello,Deris,WengHello,Deris,WengHello,Deris,WengRemovethesidesRemovetheleftsideRemovetherightsideKnowledgePointsOutputresult:知识点【字符串操作】-8.按标志分割字符串12print("Hello,Deris,Weng".split(","))

print("Hello,Deris,Weng".split("e"))【例】字符串用逗号分割['Hello','Deris','Weng']['H','llo,D','ris,W','ng']输出结果：按，按字符e[Stringmanipulation]-8.SplitstringbyflagKnowledgePoints12print("Hello,Deris,Weng".split(","))

print("Hello,Deris,Weng".split("e"))['Hello','Deris','Weng']['H','llo,D','ris,W','ng']accordingto“,”accordingtostring“e”[Example]SeparatestringswithcommasOutputresult:Python语言程序设计【字符串运算符+字符串格式化%】PythonLanguageProgramming[Stringoperators+stringformatting%]运

算

符描

述+字符串连接*字符串倍增[]通过索引获取字符串中的字符[:]截取字符串中的一部分in如果字符串中包含给定的字符，返回Truenotin如果字符串中不包含给定的字符，返回Truer/R原始字符串：所有的字符串都直接按照字面的意思来使用，没有转义特殊或不能打印的字符。原始字符串除在字符串的第一个引号前加上字母“r”（大小写均可）以外，与普通字符串有着几乎完全相同的语法%格式字符串知识点【字符串支持的常用运算符】operatorDescription+stringconcatenation*Stringmultiplication[]Getthecharactersinthestringbyindexingthe[:]InterceptsaportionofastringinReturnsTrueifthestringcontainsthegivencharacternotinReturnsTrueifthestringdoesnotcontainthegivencharacterr/ROriginalstring:Allstringsareusedliterallywithoutescapingspecialorunprintablecharacters.Theoriginalstringhasalmostthesamesyntaxastheordinarystring,exceptthattheletter"r"isaddedbeforethefirstquotationmarkofthestring(caseisacceptable)%formatstringKnowledgePoints[CommonOperatorsSupportedbyString]示例12345678910111213141516a="Deris"

b="Weng"

print("a+b输出结果：",a+b)

print("a*2输出结果：",a*2)

print("a[1]输出结果：",a[1])

print("a[1:4]输出结果：",a[1:4])

if("D"ina):

print("D在字符串a中")

else:

print("D不在字符串a中")

if("W"notina):

print("W不在字符串a中")

else:

print(“W在字符串a中")

print(r'\n')

print(R'\n')【例】字符串常用运算a+b输出结果：DerisWenga*2输出结果：DerisDerisa[1]输出结果：ea[1:4]输出结果：eriD在字符串a中W不在字符串a中\n\n输出结果：【字符串支持的常用运算符】Example12345678910111213141516a="Deris"

b="Weng"

print("a+boutputresult:",a+b)

print("a*2Outputresult:",a*2)

print("a[1]Outputresult:",a[1])

print("a[1:4]outputresult:",a[1:4])

if("D"ina):

print("Dinstringa")

else:

print("Disnotinthestringa")

if("W"notina):

print("Wisnotinthestringa")

else:

print("Winstringa")

print(r'\n')

print(R'\n')[Example]CommonoperationsonstringsA+bOutputresult:DerisWengA*2Outputresult:DerisDerisA[1]Outputresult:eA[1:4]Outputresult:eriDinstringaWisnotinthestringa\n\n[CommonOperatorsSupportedbyString]Outputresult:知识点【字符串格式化】-%1print("我叫%s,今年%d岁。"%('DerisWeng',18))【例】字符串格式符%s应用我叫DerisWeng,今年18岁。输出结果：Python支持格式化字符串的输出。最基本的用法是将一个值插入一个有字符串格式符

%的字符串中。[StringFormatting]-%1print("Mynameis%s,andI'm%dyearsoldthisyear."%('DerisWeng',18))[Example]Applicationofstringformatter%sMynameisDerisWeng.I'm18yearsold.Pythonsupportsformattedstringoutput.Themostbasicuseistoinsertavalueintoastringwiththestringformattingcharacter%.KnowledgePointsOutputresult:知识点【字符串格式化】-%符

号描

述%c格式化字符及其ASCII码%s格式化字符串%d格式化整数%u格式化无符号整型数%o格式化无符号八进制数%x格式化无符号十六进制数%X格式化无符号十六进制数（大写）符

号描

述%f格式化浮点数字，可指定小数点后的精度%e用科学记数法格式化浮点数%E作用同%e，用科学记数法格式化浮点数%g%f和%e的简写%G%f和%E的简写%p用十六进制数格式化变量的地址[StringFormatting]-%SymbolDescription%cFormattingcharactersandtheirASCIIcodes%sformattingstrings%dformattingintegers%uformattinganunsignedinteger%oformattinganunsignedoctalnumber%xformattinganunsignedhexadecimalnumber%XFormattingunsignedhexadecimalnumbers(uppercase)SymbolDescription%fFormatsfloating-pointnumbers,specifyingtheprecisionafterthedecimalpoint%eformattingfloating-pointnumbersinscientificnotation%ESameas%e,usescientificnotationtoformatfloatingpointnumbers%g%Shortforfand%e%G%Shortforfand%E%pAddressesofvariablesformattedashexadecimalnumbersKnowledgePoints示例12price=108.8528

print("该商品的售价为：%.2f"%price)【例】字符串格式符%f应用该商品的售价为：108.85输出结果：字符串格式化符号%f可指定小数点后的精度。【字符串格式化】-%Example12price=108.8528

print("Thesellingpriceofthisproductis:%.2f"%price)[Example]Applicationofstringformatter%fThesellingpriceofthisitemis:108.85Thestringformattingsymbol%fspecifiestheprecisionafterthedecimalpoint.[StringFormatting]-%Outputresult:Python语言程序设计【字符串格式化（format函数）】PythonLanguageProgrammingStringFormat(formatfunction)知识点【字符串格式化】-format函数format()方法中模板字符串的槽除了包括参数序号，还可以包括格式控制信息。此时，槽的内部样式如下：{<参数序号>:<格式控制标记>}其中，格式控制标记用来控制参数显示时的格式。格式控制标记包括：<填充><对齐><宽度>,<.精度><类型>6个字段，这些字段都是可选的，可以组合使用，这里按照使用方式逐一介绍。KnowledgePointsFormatString-formatfunctionTheslotofthetemplatestringintheformat()methodcanincludenotonlytheparameterserialnumber,butalsotheformatcontrolinformation.Atthistime,theinternalstyleoftheslotisasfollows:{<ParameterSN>:<FormatControlMark>}Theformatcontroltagsareusedtocontroltheformatoftheparameterdisplay.Formatcontroltagsinclude:<fill><alignment><width>,<.Precision><Type>6fields,thesefieldsareoptional,canbeusedincombination,hereinaccordancewiththeuseofthewaytointroduceonebyone.知识点【字符串格式化】-format函数123456#占位符{}，默认顺序

print('{}{}'.format('one','two'))

print('我的姓名为{},年龄{}岁,爱好{}'.format('DerisWeng','18','dancing'))

#占位符{}，指定顺序

print('{1}{0}'.format('one','two'))

print('我的姓名为{0},年龄{1}岁,爱好{2}'.format('DerisWeng','18','dancing'))【例】字符串格式符format函数应用onetwo我的姓名为DerisWeng,年龄18岁,爱好dancingtwoone我的姓名为DerisWeng,年龄18岁,爱好dancing123456#Placeholders{},defaultorder

print('{}{}'.format('one','two'))

print'Mynameis{},ageis{},hobbyis{}'.format('DerisWeng','18','dancing'))

#Placeholder{},specifyingtheorderinwhichthe

print('{1}{0}'.format('one','two'))

print'Mynameis{0},ageis{1},hobbyis{2}'.format('DerisWeng','18','dancing'))[Example]ApplicationofstringformatterformatfunctiononetwoMynameisDerisWeng.I'm18yearsold.IlikedancingtwooneMynameisDerisWeng.I'm18yearsold.IlikedancingKnowledgePointsFormatString-formatfunction示例【字符串格式化】-format函数123456789s='DerisWeng'

#默认左对齐，占30个字符

print('{:30}'.format(s))

#默认左对齐，占30个字符，此处逗号表示两个字符串按顺序显示

print('{:30}'.format(s),'abc')

#右对齐，占30个字符

print('{:>30}'.format(s))

#填充字符为-，^表示以居中方式显示，所有字符占30个位置

print('{:-^30}'.format(s))【例】字符串格式符format函数应用DerisWengDerisWengabcDerisWeng----------DerisWeng-----------ExampleFormatString-formatfunction123456789s='DerisWeng'

#Defaultleft-justified,30characters

print('{:30}'.format(s))

#Defaultleft-justified,occupies30characters,herethecommaindicatesthatthetwostringsaredisplayedinorder

print('{:30}'.format(s),'abc')

#Right-aligned,30characters

print('{:>30}'.format(s))

#Filledwith-,^characterstoindicatecentereddisplay,withallcharactersoccupying30positions

print('{:-^30}'.format(s))[Example]ApplicationofstringformatterformatfunctionDerisWengDerisWengabcDerisWeng----------DerisWeng-----------示例【字符串格式化】-format函数1234567891011s='DerisWeng'

#填充字符为-，>表示以靠右方式显示，所有字符占20个位置

print('{:->20}'.format(s))

#填充字符为+，<表示以靠左方式显示，所有字符占20个位置

print('{:+<20}'.format(s))

#填充字符为q，<表示以靠左方式显示，所有字符占20个位置

print('{:q<20}'.format(s))

#填充字符为1，<表示以靠左方式显示，所有字符占20个位置

print('{:1<20}'.format(s))

#填充字符为*，>表示以靠右方式显示，所有字符占20个位置

print('{:*>20}'.format(s))【例】字符串格式符format函数应用-----------DerisWengDerisWeng+++++++++++DerisWengqqqqqqqqqqqDerisWeng11111111111***********DerisWeng1234567891011s='DerisWeng'

#Filledwith-,>characterstoindicatearight-handeddisplay,withallcharactersoccupying20positions

print('{:->20}'.format(s))

#Filledwith+,<characterstoindicatethattheyaredisplayedinaleft-handedmanner,withallcharactersoccupying20positions

print('{:+<20}'.format(s))

#Thefillingcharacterisq,<indicatesthatitisdisplayedontheleft,andallcharactersoccupy20positions

print('{:q<20}'.format(s))

#Fillcharacteris1,<meansdisplayinleft-handedmode,allcharactersoccupy20positions

print('{:1<20}'.format(s))

#Filledcharacters*,>indicatethattheyaredisplayedinaright-handedmanner,withallcharactersoccupying20positions

print('{:*>20}'.format(s))[Example]Applicationofstringformatterformatfunction-----------DerisWengDerisWeng+++++++++++DerisWengqqqqqqqqqqqDerisWeng11111111111***********DerisWengExampleFormatString-formatfunction示例【字符串格式化】-format函数12345678910#保留小数点后两位

print('{:.2f}'.format(12345678))

#千分位分隔

print('{:,}'.format(12345678))

#0表示format中的索引号index

print('{0:b},{0:c},{0:d},{0:o},{0:x}'.format(42))

#0对应42，1对应50

print('{0:b},{1:c},{0:d},{1:o},{0:x}'.format(42,50))

#默认index为0

print('{:b}'.format(42))【例】字符串格式符format函数应用12345678.0012,345,678101010,*,42,52,2a101010,2,42,62,2a10101012345678910#Retaintwodecimalplaces

print('{:.2f}'.format(12345678))

#Separatedbythousandths

print('{:,}'.format(12345678))

#0indicatestheindexnumberinformat

print('{0:b},{0:c},{0:d},{0:o},{0:x}'.format(42))

#0for42,1for50#

print('{0:b},{1:c},{0:d},{1:o},{0:x}'.format(42,50))

#Thedefaultindexis0

print('{:b}'.format(42))[Example]Applicationofstringformatterformatfunction12345678.0012,345,678101010,*,42,52,2a101010,2,42,62,2a101010ExampleFormatString-formatfunction12345s='DerisWeng'

#字符串s的最大输出长度为2

print('{:.2}'.format(s))

#中文

print("{:好<20}".format(s))【例】字符串格式符format函数应用DeDerisWeng好好好好好好好好好好好示例【字符串格式化】-format函数12345s='DerisWeng'

#Themaximumoutputlengthofstringsis2

print('{:.2}'.format(s))

#Chinese

print("{:good<20}".format(s))[Example]ApplicationofstringformatterformatfunctionDeDerisWeng,good,good,good,goodExampleFormatString-formatfunction12#:冒号+空白填充+右对齐+固定宽度18+浮点精度.2+浮点数声明f

print('{:>18,.2f}'.format(70305084.0))【例】要求对70305084.0进行如下格式化：右对齐（空白填充）+固定宽度18+浮点精度.2+千分位分隔

70,305,084.00输出结果：:>18,.2f千分位、浮点数、填充字符、对齐的组合使用示例【字符串格式化】-format函数12#:colon+blankfill+rightalignment+fixedwidth18+floatingpointprecision.2+floatingpointnumberdeclarationf

print('{:>18,.2f}'.format(70305084.0))[Example]Thefollowingformattingisrequiredfor70305084.0.

right-aligned(blank-filled)+fixed-width18+floating-pointprecision.2+thousandthsseparator

70,305,084.00:>18,.2fThecombineduseofthousandths,floating-pointnumbers,paddedcharacters,alignedExampleFormatString-formatfunctionOutputresult:12data=[4,8,15,16,23,42]

print('{d[4]}{d[5]}'.format(d=data))【例】复杂数据格式化——列表数据2342输出结果：示例【字符串格式化】-format函数12data=[4,8,15,16,23,42]

print('{d[4]}{d[5]}'.format(d=data))[Example]ComplexDataFormatting-ListData2342ExampleFormatString-formatfunctionOutputresult:1234classPlant(object):

type='Student'

kinds=[{'name':'Deris'},{'name':'Christopher'}]

print('{p.type}:{p.kinds[0][name]}'.format(p=Plant()))【例】复杂数据格式化——字典数据Student:Deris输出结果：示例【字符串格式化】-format函数1234classPlant(object):

type='Student'

kinds=[{'name':'Deris'},{'name':'Christopher'}]

print('{p.type}:{p.kinds[0][name]}'.format(p=Plant()))[Example]ComplexDataFormatting-DictionaryDataStudent:DerisExampleFormatString-formatfunctionOutputresult:1234data={'first':‘Deris','last':‘Weng','last2':‘Good'}

print('{first}{last}{last2}'.format(**data))

#format(**data)等价于format(first='Deris',last='Weng',last2='Good')【例】通过字典设置参数DerisWengGood输出结果：示例【字符串格式化】-format函数1234data={'first':‘Deris','last':‘Weng','last2':‘Good'}

print('{first}{last}{last2}'.format(**data))

#Format(**data)isequivalenttoformat(first='Deris',last='Weng',last2='Good')[Example]SettingparametersbydictionaryDerisWengGoodExampleFormatString-formatfunctionOutputresult:12my_list=['Python','www.P']

print("网站名：{0[0]},地址{0[1]}".format(my_list))【例】通过列表索引设置参数网站名：Python,地址www.P输出结果：示例【字符串格式化】-format函数print("网站名：{d[0]},地址{d[1]}".format(d=my_list))12my_list=['Python','www.P']

print("Websitename:{0[0]},address:{0[1]}".format(my_list))[Example]SettingparametersbylistindexWebsitename:Python,address:www.Python.comprint("Websitename:{d[0]},address:{d[1]}".format(d=my_list))ExampleFormatString-formatfunctionOutputresult:1print("{}对应的位置是{{0}}".format("Deris"))【例】使用花括号{}

来转义花括号Deris对应的位置是{0}输出结果：示例【字符串格式化】-format函数1print(thecorrespondingpositionof"{}"is{{0}}".format("Deris"))[Example]Usethecurlybraces{}toescapethecurlybracesDeriscorrespondsto{0}ExampleFormatString-formatfunctionOutputresult:123print('{:.{}}'.format('DerisWeng',7))

#等价于

print('{:.7}'.format('DerisWeng'))【例】控制长度的两种等效做法DerisWeDerisWe输出结果：示例【字符串格式化】-format函数123print('{:.{}}'.format('DerisWeng',7))

#Equivalent

print('{:.7}'.format('DerisWeng'))[Example]TwoequivalentmethodsforcontrollinglengthDerisWeDerisWeExampleFormatString-formatfunctionOutputresult:Python语言程序设计65《利用文本文件读写存储游戏过程日志》PythonLanguageProgramming66Readingandwritingstoredgameprocedurelogsusingtextfiles知识要点67利用文本文件读写存储游戏过程日志知识点6文本文件读写重要方法有：open、close、read、write、readline、readlines【例】将字符串写入到文件test.txt中#打开一个文件

f=open(“test.txt","w")

f.write("Python是一个非常好的语言。\n是的，的确非常好!!\n")

#关闭打开的文件f.close()第一个参数为要打开的文件名。第二个参数描述文件如何使用的字符。

‘r’以只读方式打开文件，‘w’打开一个文件，只用于写(如果存在同名文件则将被删除),'a'用于追加文件内容;所写的任何数据都会被自动增加到末尾.'r+'同时用于读写。'r'将是默认值。KnowledgePoints68ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6Importantmethodsforreadingandwritingtextfilesare.open、close、read、write、readline、readlines[Example]Writethestringtothefiletest.txt#Openafile

f=open(“test.txt","w")

f.write("Pythonisaverygoodlanguage.\nYes,verygoodindeed!!!!\n")

#Closetheopenfilef.close()Thefirstargumentisthenameofthefiletobeopened.Thesecondparameterdescribeshowthefileusesthecharacters.

'r'Openthefileasread-only,'w'opensafileforwritingonly(ifafilewiththesamenameexists,itwillbedeleted),'a'isusedtoappendfilecontent;Anydatawrittenwillbeautomaticallyaddedtotheend'r+'isalsousedforreadingandwriting.'R'willbethedefaultvalue.知识要点69考一考提问环节、答题有加分、要记笔记哦！问题1：open(filename,‘w’)，这里的w是什么意思？W代表写的方式w“只写”方式每次写都是以覆盖的方式，文件之前的内容将会被覆盖；a“添加”方式则是在文件原有内容的基础上添加，并不会覆盖原有内容，所写的任何数据都会被自动增加到文件的末尾。问题2：open(filename,‘a’)中a与w的区别？KnowledgePoints70TakeatestQuestionandanswersessions,bonuspointsforansweringquestions,andtakingnotes!Question1:open(filename,'w'),whatdoeswmeanhere?WstandsforthewayofwritingW"Writeonly"modeEverywriteisoverwritten,andthecontentsbeforethefilewillbeoverwritten;A"Add"meanstoaddonthebasisoftheoriginalcontentofthefilewithoutoverwritingtheoriginalcontent,Anydatawrittenisautomaticallyaddedtotheendofthefile.Question2:Whatisthedifferencebetweenaandwinopen(filename,'a')?知识要点71利用文本文件读写存储游戏过程日志知识点61.f.read()【例】f.read()的使用#打开一个文件

f=open(“test.txt",“r")

str=f.read()print(str)#关闭打开的文件f.close()输出结果：为了读取一个文件的内容，调用f.read(size)，这将读取一定数目的数据，然后作为字符串或字节对象返回。Python是一个非常好的语言。是的，的确非常好!!KnowledgePoints721.f.read()[Example]Useoff.read()#Openafile

f=open(“test.txt",“r")

str=f.read()print(str)#Closetheopenfilef.close()Outputresult:Toreadthecontentsofafile,callf.read(size),whichwillreadacertainnumberofdata,Itisthenreturnedasastringorbyteobject.Pythonisaverygoodlanguage.Yes,verygoodindeed!!!!ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6知识要点73利用文本文件读写存储游戏过程日志知识点61.f.read()【例】f.read(size)的使用#打开一个文件

f=open(“test.txt",“r")

str=f.read(2)print(str)#关闭打开的文件f.close()输出结果：为了读取一个文件的内容，调用f.read(size)，这将读取一定数目的数据，然后作为字符串或字节对象返回。PyKnowledgePoints741.f.read()[Example]Useoff.read(size)#Openafile

f=open(“test.txt",“r")

str=f.read(2)print(str)#Closetheopenfilef.close()Toreadthecontentsofafile,callf.read(size),whichwillreadacertainnumberofdata,Itisthenreturnedasastringorbyteobject.PyReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6Outputresult:知识要点75利用文本文件读写存储游戏过程日志知识点62.f.readline()【例】f.readline()读出一行#打开一个文件

f=open(“test.txt",“r")

str=f.readline()print(str)#关闭打开的文件f.close()输出结果：会从文件中读取单独的一行，换行符为’\n’。它每次读出一行内容，占用的内存小，比较适合大文件。它返回的也是字符串对象。Python是一个非常好的语言。KnowledgePoints762.f.readline()[Example]f.readline()readsaline#Openafile

f=open(“test.txt",“r")

str=f.readline()print(str)#Closetheopenfilef.close()Aseparatelinewillbereadfromthefile,andthenewlinecharacteris'n'.Itreadsonelineatatime,occupiesasmallamountofmemory,andissuitableforlargefiles.Italsoreturnsastringobject.Pythonisaverygoodlanguage.ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6Outputresult:知识要点77利用文本文件读写存储游戏过程日志知识点62.f.readline()【例】f.readline()读出多行输出结果：会从文件中读取单独的一行，换行符为’\n’。它每次读出一行内容，占用的内存小，比较适合大文件。它返回的也是字符串对象。Python是一个非常好的语言。是的，的确非常好!!#打开一个文件

f=open("test.txt","r")

str=f.readline()

whilestr:

print(str,end='')

str=f.readline()

#关闭打开的文件

f.close()KnowledgePoints782.f.readline()[Example]f.readline()readsmultiplelinesPythonisaverygoodlanguage.Yes,verygoodindeed!!!!#Openafile

f=open("test.txt","r")

str=f.readline()

whilestr:

print(str,end='')

str=f.readline()

#Closetheopenfile

f.close()ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6Outputresult:Aseparatelinewillbereadfromthefile,andthenewlinecharacteris'n'.Itreadsonelineatatime,occupiesasmallamountofmemory,andissuitableforlargefiles.Italsoreturnsastringobject.知识要点79利用文本文件读写存储游戏过程日志知识点63.f.readlines()【例】f.readlines()读行输出结果：f.readlines()将返回该文件包含的所有行。它读取整个文件的所有行，并将其保存在一个列表变量中，每行作为一个元素。读取内存较大。['Python是一个非常好的语言。\n','是的，的确非常好!!\n']#打开一个文件

f=open("test.txt","r")

str=f.readlines()

print(str)

#关闭打开的文件

f.close()KnowledgePoints803.f.readlines()[Example]f.readlines()readlinef.Readlines()willreturnallthelinescontainedinthefile.Itreadsalllinesoftheentirefileandsavestheminalistvariable,witheachlineasanelement.Thereadmemoryislarge.['Pythonisaverygoodlanguage.n','Yes,verygoodindeed!!n']#Openafile

f=open("test.txt","r")

str=f.readlines()

print(str)

#Closetheopenfile

f.close()ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint6Outputresult:知识要点81利用文本文件读写存储游戏过程日志知识点63.f.readlines()【例】利用f.readlines()遍历读行输出结果：f.readlines()将返回该文件包含的所有行。它读取整个文件的所有行，并将其保存在一个列表变量中，每行作为一个元素。读取内存较大。Python是一个非常好的语言。是的，的确非常好!!#打开一个文件

f=open("test.txt","r")

str=f.readlines()

foriinstr:print(i,end='')

#关闭打开的文件

f.close()KnowledgePoints823.f.readlines()[Example]Usef.readlines()totraverseandreadlinesf.Readlines()willreturnallthelinescontainedinthefile.Itreadsalllinesoftheentirefileandsavestheminalistvariable,witheachlineasanelement.Thereadmemoryislarge.Pythonisaverygoodlanguage.Yes,verygoodindeed!!!!#Openafile

f=open("test.txt","r")

str=f.readlines()

foriinstr:print(i,end='')

#Closetheopenfile

f.close()ReadingandwritingstoredgameprocedurelogsusingtextfilesKnowledgepoint