各公司c面试题.pdf

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1、发信人：L e o n i x（L e o n）,信区：j o b标 题：中兴面试过程发信站：饮 水 思 源（2 0 0 2 年 1 1 月 2 0 日2 1:1 0:39 星期三），站内信件面试我的一个男的和一个p p j j。p p j j 不时微笑一下，另一位老沉着脸。我是学网络的，本来我想先介绍一下做的项目，后来都没有机会，只把其中两个附带介绍了一下。p p j j 好像不太懂技术，只问我最后一个项目中担任具体工作，我刚好想说，因为这个项目我做总体设计和项目管理。另一个问我I P v 6 对 V 4 的改进之处，I P v 6 的过渡技术，我们的改进方案的原 理（这是我的研究方向），U

2、 D P 的应用场合，p i n g 的实现原理（让我f t）还让我写二分法的算法（太简单了，很 f t,问了他几次证实，他有点不悦）我就很快写了一下，可能有些小错。最核然后问我想在哪儿工作，p p j j 代我回答了，对他说上海深圳都可以的。他们就是问你项目然后逮住你自己说精通的或者他懂的东西深入问一下。复旦大学网络乒协X 来源：饮水思源 b b s.s j tu.e d u.c n F R O M:so c k s,f ud a n.e d u.c n E:面 试 题 中 兴 面 试 过程.txt.m a zC+object-oriented questionsZZshury 160 20

3、04-12-5 17:40:00Q.What is pure virtual function?A class is made abstract by declaring one or more of its virtualfunctions to be pure.A pure virtual function is one with an initializerof=0 in its declarationQ Write a Struct Time where integer m,h,s are its membersstruct Time(int m;int h;int s;；how do

4、 you traverse a Btree in Backward in-order?Process the node in the right subtreeProcess the rootProcess the node in the left subtreeQ What is the two main roles of Operating System?As a resource managerAs a virtual machineQ In the derived class z which data member of the base class are visible?In th

5、e public and protected sections.What is a modifier?A modifier,also called a modifying function is a member function thatchanges the value of at least one data member.In other words,anoperation that modifies the state of an object.Modifiers are alsoknown as jmutators .Example:The function mod is a mo

6、difier in thefollowing code snippet:class test(int xz y;public:test()x=0;y=0;void mod()x=10;y=15；What is an accessor?An accessor is a class operation thatdoes not modify the state of an object.The accessor functions needtobe declared as const operationsDifferentiate between a template class and clas

7、s template.Template class:A generic definition or a parameterized class notinstantiated until the client provides the needed information.It j -sjargon for plain templates.Class template:A class template specifieshow individual classes can be constructed much like the way a classspecifies how individ

8、ual objects can be constructed.Its jargon forplain classes.When does a name clash occur?A name clash occurs when a name is defined in more than one place.For example.t twodifferent class libraries could give two different classes the samename.If you try to use many class libraries at the same time,t

9、hereisa fair chance that you will be unable to compile or link the programbecause of name clashes.Define namespace.It is a feature in C+tominimize name collisions in the global name space.This namespacekeyword assigns a distinct name to a library that allows otherlibraries to use the same identifier

10、 names without creating any namecollisions.Furthermore,the compiler uses the namespace signaturefordifferentiating the definitions.What is the use of(using i -declaration.A using declaration makes it possible to use a name from a namespacewithout the scope operator.What is an Iterator class?A class

11、that is used to traverse through the objects maintained bya container class.There arefive categories of iterators:input iterators,output iterators,forward iterators,bidirectional iterators,random access.Aniteratoris an entity that gives access to the contents of a container objectwithout violating e

12、ncapsulation constraints.Access to the contentsisgranted on a one-at-a-time basis in order.The order can be storageorder(as in lists and queues)or some arbitrary order(as in arrayindices)or according to some ordering relation(as in an orderedbinary tree).The iterator is a construct,which provides an

13、 interfacethat,when called,yields either the next element in the container,orsome value denoting the fact that there are no more elements toexamine.Iterators hide the details of access to and update of theelements of a container class.The simplest and safest iterators are those that permit read-only

14、access to the contents of a container class.List out some of the OODBMS available.GEMSTONE/OPALof Gemstone systems,ONTOS of Ontos,Objectivity of Objectivity Inc,Versant of Versant object technology,Object store of Object Design,ARDENT of ARDENT software,POET of POET software.List out some of the obj

15、ect-oriented methodologies.Object Oriented Development(00D)(Booch 1991,1994),Object Oriented Analysis and Design(OOA/D)(Coad and Yourdon 1991),Object Modelling Techniques(OMT)(Rumbaugh 1991)rObject Oriented Software Engineering(Objectory)(Jacobson 1992),0bject Oriented Analysis(00A)(Shlaer and Mello

16、r 1992),The Fusion Method(Coleman 1991).What is an incomplete type?Incomplete types refers to pointers in which there is non availabilityof theimplementation of the referenced location or it points to some locationwhose value is not available for modification.int*i=0 x400/i points to address 400*i=0

17、;/set the value of memory location pointed by i.Incomplete types are otherwise called uninitialized pointers.What is a dangling pointer?A dangling pointer arises when you use the address of an object afterits lifetime is over.This may occur in situations like returningaddresses of the automatic vari

18、ables from a function or using theaddress of the memory block after it is freed.The followingcode snippet shows this:class Sample(public:int*ptr;Sample(int i)(ptr=new int(i);-Sample()(delete ptr;void PrintVal()(cout i The value is j *ptr;)；void SomeFunc(Sample x)(cout j Say i am in someFunc endl;)in

19、t main()(Sample si=10;SomeFunc(si);si.PrintVal();)In the above example when PrintVal()function iscalled it is called by the pointer that has been freed by thedestructor in SomeFunc.Differentiate between the message and method.Message:Objects communicate by sending messages to each other.A message is

20、 sent to invoke a method.Method Provides response to a message.It is an implementation of an operation.What is an adaptor class or Wrapper class?A class that has no functionality of its own.Its member functionshidethe use of a third party software component or an object with thenon-compatible interf

21、ace or a non-object-oriented implementation.What is a Null object?It is an object of some class whose purpose is to indicate that a realobject of that classdoes not exist.One common use for a null object is a return valuefroma member function that is supposed to return an object with somespecified p

22、roperties but cannot find such an object.What is class invariant?A class invariant is a condition that defines all valid states foran object.It is a logicalcondition to ensure the correct working of a class.Class invariantsmust hold when an object is created,and they must be preserved underall opera

23、tions of the class.In particular all class invariants areboth preconditions and post-conditions for all operations or memberfunctions of the class.What do you mean by Stack unwinding?It is a process during exception handling when the destructor is calledfor alllocal objects between the place where t

24、he exception was thrown andwhere it is caught.Define precondition and post-condition to a member function.Precondition:A precondition is a condition that must be true on entryto a member function.A class is used correctly if preconditions arenever false.An operation is not responsible for doing anyt

25、hingsensible if its precondition fails to hold.For example,the interfaceinvariants of stack class say nothing about pushing yet another elementon a stack that is already full.We say that isful()is a preconditionof the push operation.Post-condition:A post-condition is a conditionthat must be true on

26、exit from a member function if the preconditionwas valid on entry to that function.A class is implemented correctlyif post-conditions are never false.For examplez after pushing anelement on the stack,we know that isempty()must necessarily hold.This is a post-condition of the push operation.What are

27、the conditions that have to be met for a condition to be aninvariant of the class?The condition should hold at the end of every constructor.The condition should hold at the end of every mutator(non-const)operation.What are proxy objects?Objects that stand for other objects are called proxy objects o

28、rsurrogates.template class Array2D(public:class ArraylD(public:T&operator (int index);const T&operator (int index)const;；ArraylD operator (int index);const ArraylD operator (int index)const;)；The following then becomes legal:Array2Ddata(10,20);cout can be overloaded.What is a node class?A node class

29、 is a class thatrrelies on the base class for services and implementation,provides a wider interface to the users than its base class,relies primarily on virtual functions in its public interfacedepends on all its direct and indirect base classcan be understood only in the context of the base classc

30、an be used as base for further derivationcan be used to create objects.A node class is a class that has added new services or functionalitybeyond the services inherited from its base class.What is an orthogonal base class?If two base classes have no overlapping methods or data they are saidto be ind

31、ependent of,or orthogonal to each other.Orthogonal in thesense means that two classes operate in different dimensions and donotinterfere with each other in any way.The same derived class mayinherit such classes with no difficulty.What is a container class?What are the types of container classes?A co

32、ntainer class is a class that is used to hold objects in memoryorexternal storage.A container class acts as a generic holder.Acontainer class has a predefined behavior and a well-known interface.Acontainer class is a supporting class whose purpose is to hide thetopology used for maintaining the list

33、 of objects in memory.When acontainer class contains a group of mixed objects,the container iscalled a heterogeneous container;when the container is holding a groupof objects that are all the same,the container is called a homogeneouscontainer.1 两个人轮流拿1 0 个硬币，每次可拿1,2,4个，拿到最后一个的为输，问有无必胜条件？答：后拿者赢2有 1

34、0 0 0 个表，每个表有若干个i te m,每 个 i te m 形 式 为（x,y）,寻找这些表中o v e rl a p pe d 的 i te m3 用一串节点存放N个数据，每个节点可放k 个数据，其中包含额外的b个数据，问 k为多少最能节省存储空间(假设N/(k-b)modl=l/2)4一个链表排序程序，补足其中一些丢失的语句（排序中不用额外的存储空间）5 一篇英文，将打乱的各段排序并写个总结，大意是吹嘘S AP 如何的好6两个仓库的进货，出货和仓库间的货物转移交易的流水帐，写出每次交易的货物数，单价，交易后仓库中的货物数和amount（货物数*单价）1.J eff and D ia

35、mond like play ing game of coins,O ne day theydesigned a new set of rules:l）T otally 1 0 coins2）O ne can take away 1,2 or 4 coins at one time by turns3）W ho takes the last loses.G iven these rules W hether the winning status is pre-determined or not解答：1：从后面开始考虑，最后肯定要留1 个才能保证自己赢2：所以要设法让对方留下2,3,5 个3：也

36、就是要自己取后留下1,4,6,7,8,9 ooo4：如果自己取后留下6,对方取2个，与（3）矛盾，所以排除65：如果自己取后留下8,对方取4个，与（3）一样情况，所以也排除86：同样，9也不行，如果我抽后剩下9,对方抽2 个，就反过来成对方抽剩成7 个了，也与（3）矛盾，所以也排除7：所以很显然，我只能抽剩1,4,78：因为只能抽后剩1,4,7才能赢，我先抽得话不可能达到这几个数，很显然，只能让对方先抽，也即是先抽的人输2.the U I specialist D afna found a problem that some of theI tems on the marketing docu

37、ment form overlapped with each other,because this form was implemented by differnt developers andthey didn t care the particular appearance of one item.P roduct managerT idav decided to write one small checking tool to generate the overlappeditems on all forms.H e called in his guy s to discuss abou

38、t it.S uppose the input is the integer coordinates(x,y)od the items(all rectangles)on one form.C onstruct an efficient methed to find out the overlapped items.H int:T he most direct way to do so is comparing each items withthe others,G iven 1 0 0 0 forms,each with 1 0 0-1 0 0 0 items on average,the

39、0(n2)algorithm is costly.S ome guru suggested that one 0(n)method could help only if 6.5 kiloby tes ex tra storage is available.O ne elite argued that he could cut down the number to 1%,I t*s now y ourturn to describe the idea,write out the pseudocodes,vertify hisalgorithm and propose more advanced

40、optimiz ation if possible.3 in a file sy stem,data need not be sequentially located in phy sicalblocks,W e use a number of tables storing nodes imformation.S upposenow we use a fix ed node siz e of variable-lenth n,it takes n/(k-b)nodes to store this item.(H ere b is a constant,signify ing thatb wor

41、ds of each node contain control information,such as a link to thenex t node).I f the avarage length n of an I tem is N,what choiseof k minimiz es the average amount of storage space required?(Assume that the average value of(n/(k-b)mod 1 is equal to 1/2 ,for anyfix ed k,as n varies)共五道题,大致如下：1 .图示从R

42、 T L sy nthesis到 tape out之间的设计flow,并列出其中各步使用的tool.2 .用 perl或 T C L/T k实现一段字符串识别和比较的程序.(唉,都不懂)3 .画出一种C M O S 的 D 锁存器的电路图和版图.4 .解释setup time和 hold time的定义和在时钟信号延迟时的变化.5 .解 释 latch-up现象和Antenna effect和其预防措施.对 n 个顶点的无向图和有向图用邻接矩阵和邻接表表示时，如何判断下列问题1)图中有多少边？2)任意两个顶点的i 和 j 是否有变相连？3)任意一个顶点的度是多少？有向图G 用邻接矩阵存储，其

43、第 i 行的所有元素之和等于顶点i 的l o 定义的解释，in t *p,in t (*p)();等 1 0 分2 o V C6.0 的单步执行的快捷键5分3 o 程序语句补全5 分(记 住 a s c ii含义)4。5o名词解释，R AM,R O M,堆栈，EEP R 0 M等 1 0 分以上的虽然不确定，但是写出来了，电路的只好硬着头皮做了。6 o MCS 8 0 5 1 实现3*4 键盘才 描和4个七段LED,画电路图和程序流程图1 0 分7 o 一个带几个电阻和一个三极管的图，选择P NP/NP N,饱和，截止，*状 态 等 1 0 分8O 一个频率什么电路的功能和带宽1 0 分9 o

44、1 0 o 一个推理，三个人，三个地方，三个 职 业 1 0 分(我写甲是外语系)准备看看数字电路。1.w in 2 k,v c+6 下，指出下面定义的含义和所占的字节数：in t a;in t a ;in t *a;in t *a ;in t (*a)口;in t (*a)();in t *a();in t *a;2 .a r r a y 和 lis t 的区别3 .列举出儿种进程调度方法，并说出区别4 .bin a r y 和 bu bble 排序算法的区别5 .软件工程的流程6 .一段翻译(英译汉)关于CD和 DV D格式的还有就编译器与解释器的区别不用画图函数画同心园并填充还有一道模电

45、和一道数电的题e a s y1.describe x86 PCs architecture in a diagramcpu_,core chipsetE_ 1 Cache_,DRAM_,IO-subsystemz IO-Bus2.SWI instruction is often called a supervisor call,describe theactionsin detaila.Save the address of the instruction after the SWI in rl4_svc.b.Save the CPSR in SPSR_svc.c.Enter supervis

46、or mode and disable IRQs.d.Set the PC to 08 and begin executing the instruction there.3.a.What is PIO operation?advantage and disadvantage?b.DMA operation?advantage and disadvantage?c.Scatter/Gather DMA engine?how does it operate?4.MP3 decoder related.(a flow chart of decoding is presented)a.advanta

47、ges of Huffman encoding?b.why the aliasing reduction is necessary?c.analytical expression in mathematics of the IMDCT?d.which block in the flow chart is suitable for the softwareimplementationand which for the hardware?reason?5.Assembly codes-C language(about 15 lines).6.Graduation thesis descriptio

48、n.1.write down the 7 types of exception and vector address of ARM.2.Briefly describe the signals(TRST#Z TCK,TMS,TD工,TDO)of JTAG.3.What is the instruction for switching the ARM processor to excuteThumbinstructions?4.f i -36IAAaeEuDa)FIR filter;b)H R filter;c)DFT(AeEC：apA4：dia1.W ha t is O S I Mo d e

49、l?W hic h la y e r is r e s p o n s ible fo r t he in fo r ma t io n r e lia bled e liv e r y?2.List the differences of TCP and U D P3.Please list the differences between convertional C language andobject-oriented language(00L),sau C+?4.Please list the three major features and meanings of C+5.Please

50、 list the program areas of the run time environment and give a briefexplanation of the function of each area6.Write a piece of code(or macro)to convert the decimal number to hex format7.In a real time operating based embedded system,2 tasks will access theRS-232C port.Design a mutual exclusive mecha