3VB和C#语法对比图(代码实例)

1、c# 和 vb.net 的语法相差还是比较大的.可能你会 c#,可能你会 vb.将它们俩放在一起对比一下你就会很快读懂, 并掌握另一门语言.相信下面这张图会对你帮助很大.commentsvb.netsinglelineonlyremsinglelineonlyc#/singleline/*multipleline*/xmlcomments on singleline/*xmlcommentson multiplelines*/data typesvb.netvaluetypesbooleanbytechar (example:a)short,integer,longsingle,doubled

2、ecimaldatereferencetypesobjectstringc#/valuetypesboolbyte,sbytechar (example:a)short,ushort,int,uint,long, ulongfloat,doubledecimaldatetime/referencetypesobjectstringdim x as integersystem.console.writeline(x.gettype()system.console.writeline(typename(x)typeconversiondim d as single= 3.5dim ias inte

3、ger= ctype (d,integer)i= cint(d)i= int(d)intx;console.writeline(x.gettype()console.writeline(typeof(int)/typeconversionfloatd = 3.5;inti= (int)dconstantsvb.netconst max_authorsas integer= 25readonly min_rank as single= 5.00c#constintmax_authors= 25;readonlyfloatmin_ranking = 5.00;enumerationsvb.nete

4、numactionstartstopisa reservedwordstoprewindforwardend enumenumstatusflunk = 50c#enumactionstart,stop,rewind,forward;enumstatusflunk= 50, pass = 70,excel = 90;pass = 70excel = 90end enumdim a as action= action.stopifa action.startthen _printsstopis1system.console.writeline(a.tostring& is & a

5、)prints70system.console.writeline(status.pass)printspasssystem.console.writeline(status.pass.tostring()actiona = action.stop;if(a != action.start)/printsstopis1system.console.writeline(a+ is + (int)a);/prints70system.console.writeline(int)status.pass);/printspasssystem.console.writeline(status.pass)

6、;operatorsvb.netcomparison=arithmetic+-*/mod(integerdivision)(raiseto a power)assignment=+=-=*=/=c#/comparison=!=/arithmetic+-*/%(mod)/(integerdivisionifbothoperands are ints)math.pow(x,y)/assignment=&=bitwiseandandalsoororelsenotlogicalandandalsoororelsenotstringconcatenation&=+=-=*=/=%=&am

7、p;=|=+-/bitwise&|/logical&|!/stringconcatenation+choicesvb.netgreeting= iif(age 20, whatsup?,hello)one linedoesntrequireendif,no elseiflanguage = vb.net thenlangtype = verboseuse:to put two commandson samelineifx 100 and y 5 then x *= 5 :y *= 2c#greeting= age 20 ? whatsup? :hello;if(x != 100

8、 & y 5)preferredifx 100 and y 5 thenx *= 5y *= 2end iforto break up any longsinglecommanduse _ifhenyouhaveareally linesthen _usetheunderscore(chartobreakitup)ifx 5 thenx *= yelseifx = 5 thenx += yelseifx 5)x *= y;elseif(x = 5)x += y;elseif(x 10)x -= y;elsex /= y;/mustbe integeror stringswitch(co

9、lor)case black:case red:r+;break;case bluebreak;case green:g+;case black,redr += 1case blueb += 1case greeng += 1case elseother+= 1end selectbreak;default:other+;break;loopsvb.netpre-testloops:while c 10c += 1end while do untilc = 10c+= 1looppost-testloop:do while c 10c += 1loopfor c = 2 to 10 step

10、2system.console.writeline(c)nextarrayor collectionloopingc#/pre-testloops: while(i 10)i+;for(i= 2; i = 10; i+= 2)system.console.writeline(i);/post-testloop:doi+;while(i 10);dim namesas string()= steven,suok,sarahfor each s as stringin namessystem.console.writeline(s)next/arrayor collectionloopingstr

11、ingnames = steven,suok,sarah;foreach(strings innames)system.console.writeline(s);arraysvb.netdim nums() as integer= 1,2, 3for i asinteger= 0 to nums.length- 1console.writeline(nums(i)next4isthe indexof the lastelement,so itholds5 elementsdim names(4) as stringnames(0) = steventhrowssystem.indexoutof

12、rangeexceptionnames(5) = sarahresizethe array,keeping theexistingvalues(preserveisoptional)redimpreservenames(6)c#intnums = 1,2, 3;for(inti = 0; i nums.length; i+)console.writeline(numsi);/5 isthe sizeof the arraystringnames = new string5;names0 = steven;/throwssystem.indexoutofrangeexceptionnames5

13、= sarah/c# cantdynamicallyresizeanarray./justcopy intonew array.stringnames2= new string7;/or names.copyto(names2, 0);array.copy(names,names2,names.length);float,twod = new floatrows,dimtwod(rows-1,cols-1)as singletwod(2,0) = 4.5dim jagged()()as integer= _newinteger(4),newinteger(1),newinteger(2) ja

14、gged(0)(4)= 5cols;twod2,0= 4.5;intjagged = new int3new int5,new int2,newint3;jagged04= 5;functionsvb.netpassby value(in,default),reference(in/out),and reference(out)sub testfunc(byvalx as integer,byref y as integer,byref z as integer)x += 1y += 1z = 5end subcsetto zero by defaultdim a = 1, b = 1, c

15、as integertestfunc(a,b, c)system.console.writeline(012,a, b, c) 12 5acceptvariablenumber ofargumentsc#/pass by value(in,default),reference/(in/out),and reference(out)voidtestfunc(intx,refinty,outintz) x+;y+;z = 5;inta = 1, b = 1, c; /c doesntneedinitializingtestfunc(a,refb, out c);system.console.wri

16、teline(012,a, b, c);/1 2 5/accept variablenumber ofargumentsfunctionsum(byval paramarraynums as integer()as integersum= 0for each ias integerin numssum+= inextend functionoruse a returnstatementlikec#dimtotalas integer= sum(4, 3, 2,1) returns10optionalparametersmust belistedlastandmust have a defaul

17、tvaluesubsayhello(byvalnameas string,optionalbyval prefixas string=)system.console.writeline(greetings, & prefix& & name)end subsayhello(steven,dr.)sayhello(suok)intsum(params intnums) intsum = 0;foreach(intiinnums)sum += i;returnsum;int total=sum(4, 3, 2, 1); / returns10/*c# doesntsuppo

18、rtoptionalarguments/parameters.just create two differentversionsofthe same function.*/voidsayhello(stringname, stringprefix)system.console.writeline(greetings, + prefix+ + name);voidsayhello(stringname) sayhello(name,);exceptionhandlingvb.netdeprecatedunstructurederrorhandlingc#on errorgoto myerrorh

19、andler.myerrorhandler:system.console.writeline(err.description)dimex as newexception(somethinghas reallygone wrong.)throw extryy = 0 x = 10 / ycatch ex as exceptionwheny = 0argumentand whenisoptionalsystem.console.writeline(ex.message)finallydosomething()end tryexceptionup = newexception(somethingis

20、reallywrong.);throw up; /ha hatryy = 0;x = 10 /y;catch (exceptionex) /argumentisoptional,no when keywordconsole.writeline(ex.message);finally/do somethingnamespacesvb.netnamespaceaspalliance.dotnet.community.end namespaceorc#namespaceaspalliance.dotnet.community./ornamespaceaspalliancenamespacedotne

21、tnamespacecommunity.end namespaceend namespaceend namespaceimportsaspalliance.dotnet.communitynamespaceaspalliancenamespacedotnet namespace community .usingaspalliance.dotnet.community;classes/ interfacesvb.netaccessibilitykeywordspublicprivatefriendprotectedprotectedfriendsharedinheritanceclass art

22、iclesinheritsauthors.end classinterfacedefinitioninterfaceiarticle.c#/accessibilitykeywordspublicprivateinternalprotectedprotectedinternalstatic/inheritanceclassarticles:authors./interfacedefinitioninterfaceiarticle.end interfaceextendingan interfaceinterfaceiarticleinheritsiauthor.end interfaceinte

23、rfaceimplementationclass publicationdateimplementsiarticle,irating.end class/extendingan interfaceinterfaceiarticle:iauthor./interfaceimplementationclasspublicationdate:iarticle,irating.constructors/ destructorsvb.netclass topauthorprivate_topauthoras integerpublicsub new()_topauthor= 0end subpublic

24、sub new(byval topauthoras integer)me._topauthor= topauthorend subprotectedoverridessubfinalize()c#classtopauthor privateint_topauthor;publictopauthor()_topauthor= 0;publictopauthor(inttopauthor)this._topauthor=topauthortopauthor()/destructorcode to freeunmanagedresources.desctructorcode to freeunman

25、agedresourcesmybase.finalize()end subend class/implicitlycreatesafinalizemethodobjectsvb.netdim authoras topauthor = newtopauthorwith author.name = steven.authorranking= 3end withauthor.rank(scott)author.demote()callingsharedmethodortopauthor.rank()dim author2as topauthor = authorbothreferto same ob

26、jectauthor2.name = joesystem.console.writeline(author2.name) printsjoeauthor= nothing freethe objectifauthorisnothingthen _c#topauthor author= new topauthor();/nowithconstructauthor.name = steven;author.authorranking= 3;author.rank(scott);topauthor.demote()/callingstaticmethodtopauthor author2= auth

27、or/bothreferto same objectauthor2.name = joe;system.console.writeline(author2.name) /printsjoeauthor= null/freethe objectif(author= null)author= newtopauthordim obj as object= newtopauthoriftypeof obj is topauthor then _system.console.writeline(isa topauthor object.)author= new topauthor();objectobj

28、= new topauthor();if(objistopauthor)systconsole.writeline(isatopauthor object.);structsvb.netstructureauthorrecordpublicnameas stringpublicrank as singlepublicsub new(byval nameasstring,byval rank as single)m= nameme.rank = rankend subend structuredim authoras authorrecord = newauthorrecord(st

29、even,8.8)dim author2as authorrecord== scottsystem.console.writeline() printsstevensystem.console.writeline() printsscottc#structauthorrecordpublicstringname;publicfloatrank;publicauthorrecord(stringname,floatrank)= name;this.rank= rank;authorrecord a

30、uthor= newauthorrecord(steven,8.8);authorrecord author2= = scott;systemconsole.writeline();/printsstevensystem.console.writeline(); /printsscottpropertiesvb.netprivate_sizeas integerpublicpropertysize()as integergetreturn _sizeend getset (byvalvalue as integer

31、)ifvalue 0 then_size= 0else_size= valueend ifend setend propertyfoo.size+= 1c#privateint_size;publicintsize get return_size;set if(value 0)_size= 0;else_size= value;foo.size+;delegates/eventsvb.netdelegatesubmsgarrivedeventhandler(byvalmessageas string)event msgarrivedeventasmsgarrivedeventhandlerc#

32、delegatevoidmsgarrivedeventhandler(stringmessage);event msgarrivedeventhandlermsgarrivedevent;orto definean event whichdeclaresadelegateimplicitlyevent msgarrivedevent(byvalmessage as string)addhandler msgarrivedevent,addressof my_msgarrivedcallbackwontthrow an exceptionifobj isnothingraiseeventmsga

33、rrivedevent(testmessage)removehandler msgarrivedevent,addressof my_msgarrivedcallbackimportssystem.windows.formswitheventscantbe used on localvariabledim withevents mybutton as buttonmybutton = newbuttonprivatesub mybutton_click(byvalsender as system.object,_byval e as system.eventargs)handles mybut

34、ton.clickmessagebox.show(me,button/delegatesmust be used with eventsinc#msgarrivedevent+= newmsgarrivedeventhandler(my_msgarrivedeventcallback);/throwsexceptionifobjisnullmsgarrivedevent(testmessage);msgarrivedevent-= newmsgarrivedeventhandler(my_msgarrivedeventcallback);usingsystem.windows.forms;bu

35、ttonmybutton = new button();mybutton.click+= newsystem.eventhandler(mybutton_click);privatevoidmybutton_click(objectsender,system.eventargse) messagebox.show(this,button wasclicked,info,messageboxbuttons.ok,messageboxicon.information);was clicked,info,_messageboxbuttons.ok,messageboxicon.information

36、)end subconsole i/ovb.netspecialcharacterconstantsvbcrlf,vbcr,vblf,vbnewlinevbnullstringvbtabvbbackvbformfeedvbverticaltabchr(65)returnsasystem.console.write(whatsyour name?)dim nameas string=system.console.readline()system.console.write(howold areyou? )dim age as integer=val(system.console.readline

37、()system.console.writeline(0is1years old.,name, age)orsystem.console.writeline(name& is & age & years old.)dim c as integerc#/escapesequencesn, rtconvert.tochar(65)/returnsa- equivalenttochr(num) invb/or(char)65system.console.write(whatsyourname?);stringname =system.console.readline();sy

38、stem.console.write(howold areyou? );intage =convert.toint32(system.console.readline();system.console.writeline(0is 1years old.,name, age);c = system.console.read()readsinglecharsystem.console.writeline(c)prints65 ifuser entersa/orsystem.console.writeline(name+ is +age + years old.);int c = system.console.read();/readsinglecharsystem.console.writeline(c);/prints65 ifuser entersafilei/ovb.netimportssystem.iowriteout to textfiledim writeras streamwriter=