DynamicObjects动态对象

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1、DynamicObjectsProgrammingMemoryManagementStaticMemoryAllocationMemoryisallocatedatcompilationtimeDynamicMemoryMemoryisallocatedatrunningtimeConceptualViewofMemory(DYNAMICMEMORY)Staticvs.DynamicObjectsStaticobjectMemoryisacquiredautomaticallyMemoryisreturnedautomaticallywhenobjectgoesout

2、ofscopeDynamicobjectMemoryisacquiredbyprogramwithanallocationrequestnewoperationDynamicobjectscanexistbeyondthefunctioninwhichtheywereallocatedObjectmemoryisreturnedbyadeallocationrequestdeleteoperationMemoryAllocation{inta[200];…}int*ptr;ptr=newint[200];…delete[]ptr;newdeleteObject(var

3、iable)creation:NewSyntaxptr=newSomeType;whereptrisapointeroftypeSomeTypepUninitializedintvariableExampleint*p=newint;Object(variable)destruction:DeleteSyntaxdeletep;storagepointedtobypisreturnedtofreestoreandpisnowundefinedpExampleint*p=newint;*p=10;deletep;10ArrayofNew:dynamicarraysSyn

4、taxP=newSomeType[Expression];WherePisapointeroftypeSomeTypeExpressionisthenumberofobjectstobeconstructed--wearemakinganarrayBecauseoftheflexiblepointersyntax,PcanbeconsideredtobeanarrayExampleDynamicMemoryAllocationRequestfor“unnamed”memoryfromtheOperatingSystemint*p,n=10;p=newint;p=n

5、ewint[100];pnewpnewp=newint[n];pnewMemoryAllocationExampleNeedanarrayofunknownsizemain(){cout<<“Howmanystudents?“;cin>>n;int*grades=newint[n];for(inti=0;i>mark;grades[i]=mark;}...printMean(grades,n);//callafunctionwithdynamic

6、array...}Freeing(ordeleting)MemoryASimpleDynamicListExamplecout<<"Enterlistsize:";intn;cin>>n;int*A=newint[n];if(n<=0){cout<<"badsize"<

7、izevoidinitialize(intlist[],intsize,intvalue){for(inti=0;i