An array of clone (identical) objects.

Memory for the objects stored in the array is allocated only once in the lifetime of the clones array. All objects must be of the same class. For the rest this class has the same properties as TObjArray.

To reduce the very large number of new and delete calls in large loops like this (O(100000) x O(10000) times new/delete):

TObjArray a(10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      a[i] = new TTrack(x,y,z,...);
      ...
      ...
   }
   ...
   a.Delete();
}

One better uses a TClonesArray which reduces the number of new/delete calls to only O(10000):

TClonesArray a("TTrack", 10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      new(a[i]) TTrack(x,y,z,...);
      ...
      ...
   }
   ...
   a.Delete(); // or a.Clear() or a.Clear("C")
}

To reduce the number of call to the constructor (especially useful if the user class requires memory allocation), the object can be added (and constructed when needed) using ConstructedAt which only calls the constructor once per slot.

TClonesArray a("TTrack", 10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      TTrack *track = (TTrack*)a.ConstructedAt(i);
      track->Set(x,y,z,....);
      ...
      ...
   }
   ...
   a.Clear(); // or a.Clear("C");
}

Note: the only supported way to add objects to a TClonesArray is via the new with placement method or the ConstructedAt method. The other Add() methods ofTObjArray and its base classes are not allowed.

Considering that a new/delete costs about 70 mus on a 300 MHz HP, O(10^9) new/deletes will save about 19 hours.

NOTE 1

C/C++ offers the possibility of allocating and deleting memory. Forgetting to delete allocated memory is a programming error called a "memory leak", i.e. the memory of your process grows and eventually your program crashes. Even if you always delete the allocated memory, the recovered space may not be efficiently reused. The process knows that there are portions of free memory, but when you allocate it again, a fresh piece of memory is grabbed. Your program is free from semantic errors, but the total memory of your process still grows, because your program's memory is full of "holes" which reduce the efficiency of memory access; this is called "memory fragmentation". Moreover new / delete are expensive operations in terms of CPU time.

Without entering into technical details, TClonesArray allows you to "reuse" the same portion of memory for new/delete avoiding memory fragmentation and memory growth and improving the performance by orders of magnitude. Every time the memory of the TClonesArray has to be reused, the Clear() method is used. To provide its benefits, each TClonesArray must be allocated once per process and disposed of (deleted) only when not needed any more.

So a job should see only one deletion for each TClonesArray, which should be Clear()ed during the job several times. Deleting a TClonesArray is a double waste. Not only you do not avoid memory fragmentation, but you worsen it because the TClonesArray itself is a rather heavy structure, and there is quite some code in the destructor, so you have more memory fragmentation and slower code.

NOTE 2

When investigating misuse of TClonesArray, please make sure of the following:

Use Clear() or Clear("C") instead of Delete(). This will improve program execution time.
TClonesArray object classes containing pointers allocate memory. To avoid causing memory leaks, special Clear("C") must be used for clearing TClonesArray. When option "C" is specified, ROOT automatically executes the Clear() method (by default it is empty contained in TObject). This method must be overridden in the relevant TClonesArray object class, implementing the reset procedure for pointer objects.
If the objects are added using the placement new then the Clear must deallocate the memory.
If the objects are added using TClonesArray::ConstructedAt then the heap-based memory can stay allocated and reused as the constructor is not called for already constructed/added object.
To reduce memory fragmentation, please make sure that the TClonesArrays are not destroyed and created on every event. They must only be constructed/destructed at the beginning/end of the run.

Definition at line 32 of file TClonesArray.h.

Public Types
enum	{ kForgetBits = BIT(0), kNoSplit = BIT(1), kBypassStreamer = BIT(12) }
	Saved copies of pointers to objects. More...

Public Types inherited from TObjArray
typedef TObjArrayIter	Iterator_t

Public Types inherited from TCollection
enum	{ kInitCapacity = 16, kInitHashTableCapacity = 17 }

Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000, kNotDeleted = 0x02000000, kZombie = 0x04000000, kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0), kOverwrite = BIT(1), kWriteDelete = BIT(2) }

enum	EStatusBits { kCanDelete = BIT(0), kMustCleanup = BIT(3), kObjInCanvas = BIT(3), kIsReferenced = BIT(4), kHasUUID = BIT(5), kCannotPick = BIT(6), kNoContextMenu = BIT(8), kInvalidObject = BIT(13) }

Public Member Functions
	TClonesArray ()
	Default Constructor. More...

	TClonesArray (const char *classname, Int_t size=1000, Bool_t call_dtor=kFALSE)
	Create an array of clone objects of classname. More...

	TClonesArray (const TClass *cl, Int_t size=1000, Bool_t call_dtor=kFALSE)
	Create an array of clone objects of class cl. More...

	TClonesArray (const TClonesArray &tc)
	Copy ctor. More...

virtual	~TClonesArray ()
	Delete a clones array. More...

void	AbsorbObjects (TClonesArray *tc)
	Directly move the object pointers from tc without cloning (copying). More...

void	AbsorbObjects (TClonesArray *tc, Int_t idx1, Int_t idx2)
	Directly move the range of object pointers from tc without cloning (copying). More...

void	AddAfter (const TObject , TObject )
	Add object in the slot after object after. More...

void	AddAt (TObject *, Int_t)
	Add object at position ids. More...

void	AddAtAndExpand (TObject *, Int_t)
	Add object at position idx. More...

Int_t	AddAtFree (TObject *)
	Return the position of the new object. More...

void	AddBefore (const TObject , TObject )
	Add object in the slot before object before. More...

void	AddFirst (TObject *)
	Add object in the first slot of the array. More...

void	AddLast (TObject *)
	Add object in the next empty slot in the array. More...

TObject *	AddrAt (Int_t idx)

void	BypassStreamer (Bool_t bypass=kTRUE)
	When the kBypassStreamer bit is set, the automatically generated Streamer can call directly TClass::WriteBuffer. More...

Bool_t	CanBypassStreamer () const

virtual void	Clear (Option_t *option="")
	Clear the clones array. More...

virtual void	Compress ()
	Remove empty slots from array. More...

TObject *	ConstructedAt (Int_t idx)
	Get an object at index 'idx' that is guaranteed to have been constructed. More...

TObject *	ConstructedAt (Int_t idx, Option_t *clear_options)
	Get an object at index 'idx' that is guaranteed to have been constructed. More...

virtual void	Delete (Option_t *option="")
	Clear the clones array. More...

virtual void	Expand (Int_t newSize)
	Expand or shrink the array to newSize elements. More...

virtual void	ExpandCreate (Int_t n)
	Expand or shrink the array to n elements and create the clone objects by calling their default ctor. More...

virtual void	ExpandCreateFast (Int_t n)
	Expand or shrink the array to n elements and create the clone objects by calling their default ctor. More...

TClass *	GetClass () const

void	MultiSort (Int_t nTCs, TClonesArray **tcs, Int_t upto=kMaxInt)
	Sort multiple TClonesArrays simultaneously with this array. More...

TObject *	New (Int_t idx)
	Create an object of type fClass with the default ctor at the specified index. More...

TClonesArray &	operator= (const TClonesArray &tc)
	Assignment operator. More...

TObject *&	operator[] (Int_t idx)
	Return pointer to reserved area in which a new object of clones class can be constructed. More...

TObject *	operator[] (Int_t idx) const
	Return the object at position idx. Returns 0 if idx is out of bounds. More...

virtual TObject *	Remove (TObject *obj)
	Remove object from array. More...

virtual TObject *	RemoveAt (Int_t idx)
	Remove object at index idx. More...

virtual void	RemoveRange (Int_t idx1, Int_t idx2)
	Remove objects from index idx1 to idx2 included. More...

void	SetClass (const char *classname, Int_t size=1000)
	see TClonesArray::SetClass(const TClass*) More...

void	SetClass (const TClass *cl, Int_t size=1000)
	Create an array of clone objects of class cl. More...

virtual void	SetOwner (Bool_t enable=kTRUE)
	A TClonesArray is always the owner of the object it contains. More...

virtual void	Sort (Int_t upto=kMaxInt)
	If objects in array are sortable (i.e. More...

Public Member Functions inherited from TObjArray
	TObjArray (Int_t s=TCollection::kInitCapacity, Int_t lowerBound=0)
	Create an object array. More...

	TObjArray (const TObjArray &a)
	Create a copy of TObjArray a. Note, does not copy the kIsOwner flag. More...

virtual	~TObjArray ()
	Delete an array. More...

void	Add (TObject *obj)

TObject *	After (const TObject *obj) const
	Return the object after obj. Returns 0 if obj is last object. More...

TObject *	At (Int_t idx) const

TObject *	Before (const TObject *obj) const
	Return the object before obj. Returns 0 if obj is first object. More...

virtual Int_t	BinarySearch (TObject *obj, Int_t upto=kMaxInt)
	Find object using a binary search. More...

virtual TObject *	FindObject (const char *name) const
	Find an object in this collection using its name. More...

virtual TObject *	FindObject (const TObject *obj) const
	Find an object in this collection using the object's IsEqual() member function. More...

TObject *	First () const
	Return the object in the first slot. More...

Int_t	GetEntries () const
	Return the number of objects in array (i.e. More...

Int_t	GetEntriesFast () const

Int_t	GetLast () const
	Return index of last object in array. More...

TObject **	GetObjectRef () const

TObject **	GetObjectRef (const TObject *obj) const
	Return address of pointer obj. If obj is 0 returns address of container. More...

Int_t	IndexOf (const TObject *obj) const

Bool_t	IsEmpty () const

TObject *	Last () const
	Return the object in the last filled slot. Returns 0 if no entries. More...

Int_t	LowerBound () const

TIterator *	MakeIterator (Bool_t dir=kIterForward) const
	Returns an array iterator. More...

TObjArray &	operator= (const TObjArray &)
	Assignment operator. Note, unsets the kIsOwner flag. More...

virtual void	Randomize (Int_t ntimes=1)
	Randomize objects inside the array, i.e. More...

virtual void	RecursiveRemove (TObject *obj)
	Remove object from this collection and recursively remove the object from all other objects (and collections). More...

void	SetLast (Int_t last)
	Set index of last object in array, effectively truncating the array. More...

TObject *	UncheckedAt (Int_t i) const

Public Member Functions inherited from TSeqCollection
virtual	~TSeqCollection ()

virtual Bool_t	IsSorted () const

Int_t	LastIndex () const

Long64_t	Merge (TCollection *list)
	Merge this collection with all collections coming in the input list. More...

virtual void	RemoveAfter (TObject *after)

virtual void	RemoveBefore (TObject *before)

virtual void	RemoveFirst ()

virtual void	RemoveLast ()

void	UnSort ()

Public Member Functions inherited from TCollection
virtual	~TCollection ()

virtual void	AddAll (const TCollection *col)
	Add all objects from collection col to this collection. More...

void	AddVector (TObject *obj1,...)
	Add all arguments to the collection. More...

Bool_t	AssertClass (TClass *cl) const
	Make sure all objects in this collection inherit from class cl. More...

TIter	begin () const

void	Browse (TBrowser *b)
	Browse this collection (called by TBrowser). More...

Int_t	Capacity () const

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an collection using the Streamer facility. More...

Int_t	Compare (const TObject *obj) const
	Compare two TCollection objects. More...

Bool_t	Contains (const char *name) const

Bool_t	Contains (const TObject *obj) const

virtual void	Draw (Option_t *option="")
	Draw all objects in this collection. More...

virtual void	Dump () const
	Dump all objects in this collection. More...

TIter	end () const

virtual const char *	GetName () const
	Return name of this collection. More...

virtual Int_t	GetSize () const

virtual Int_t	GrowBy (Int_t delta) const
	Increase the collection's capacity by delta slots. More...

ULong_t	Hash () const
	Return hash value for this object. More...

Bool_t	IsArgNull (const char where, const TObject obj) const
	Returns true if object is a null pointer. More...

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...

Bool_t	IsOwner () const

Bool_t	IsSortable () const

virtual void	ls (Option_t *option="") const
	List (ls) all objects in this collection. More...

virtual TIterator *	MakeReverseIterator () const

virtual Bool_t	Notify ()
	'Notify' all objects in this collection. More...

TObject *	operator() (const char *name) const
	Find an object in this collection by name. More...

virtual void	Paint (Option_t *option="")
	Paint all objects in this collection. More...

virtual void	Print (Option_t *option="") const
	Default print for collections, calls Print(option, 1). More...

virtual void	Print (Option_t *option, Int_t recurse) const
	Print the collection header and its elements. More...

virtual void	Print (Option_t option, const char wildcard, Int_t recurse=1) const
	Print the collection header and its elements that match the wildcard. More...

virtual void	Print (Option_t *option, TPRegexp &regexp, Int_t recurse=1) const
	Print the collection header and its elements that match the regexp. More...

virtual void	RemoveAll (TCollection *col)
	Remove all objects in collection col from this collection. More...

void	RemoveAll ()

void	SetCurrentCollection ()
	Set this collection to be the globally accesible collection. More...

void	SetName (const char *name)

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write all objects in this collection. More...

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write all objects in this collection. More...

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor. More...

	TObject (const TObject &object)
	TObject copy ctor. More...

virtual	~TObject ()
	TObject destructor. More...

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad. More...

virtual const char *	ClassName () const
	Returns name of class to which the object belongs. More...

virtual void	Copy (TObject &object) const
	Copy this to obj. More...

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object. More...

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs. More...

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: `gROOT->SetSelectedPad(gPad)`. More...

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message. More...

virtual void	Execute (const char method, const char params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g. More...

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray. More...

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py). More...

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message. More...

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object. More...

virtual const char *	GetIconName () const
	Returns mime type name of object. More...

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py). More...

virtual Option_t *	GetOption () const

virtual const char *	GetTitle () const
	Returns title of object. More...

virtual UInt_t	GetUniqueID () const
	Return the unique object id. More...

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out. More...

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message. More...

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname". More...

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl. More...

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas. More...

void	InvertBit (UInt_t f)

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory). More...

Bool_t	IsOnHeap () const

Bool_t	IsZombie () const

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete. More...

void	operator delete (void *ptr)
	Operator delete. More...

void	operator delete[] (void *ptr)
	Operator delete []. More...

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator. More...

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list. More...

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory. More...

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename. More...

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out". More...

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f. More...

void	SetBit (UInt_t f)

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object. More...

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id. More...

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message. More...

Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message. More...

Protected Attributes
TClass *	fClass

TObjArray *	fKeep
	Pointer to the class of the elements. More...

Protected Attributes inherited from TObjArray
TObject **	fCont

Int_t	fLast

Int_t	fLowerBound
	Array contents. More...

Protected Attributes inherited from TSeqCollection
Bool_t	fSorted

Protected Attributes inherited from TCollection
TString	fName

Int_t	fSize

Additional Inherited Members
Static Public Member Functions inherited from TSeqCollection
static Int_t	ObjCompare (TObject a, TObject b)
	Compare to objects in the collection. Use member Compare() of object a. More...

static void	QSort (TObject **a, Int_t first, Int_t last)
	Sort array of TObject pointers using a quicksort algorithm. More...

static void	QSort (TObject a, TObject b, Int_t first, Int_t last)

static void	QSort (TObject a, Int_t nBs, TObject *b, Int_t first, Int_t last)
	Sort array a of TObject pointers using a quicksort algorithm. More...

Static Public Member Functions inherited from TCollection
static void	EmptyGarbageCollection ()
	Do the garbage collection. More...

static void	GarbageCollect (TObject *obj)
	Add to the list of things to be cleaned up. More...

static TCollection *	GetCurrentCollection ()
	Return the globally accessible collection. More...

static void	StartGarbageCollection ()
	Set up for garbage collection. More...

Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag. More...

static Bool_t	GetObjectStat ()
	Get status of object stat flag. More...

static void	SetDtorOnly (void *obj)
	Set destructor only flag. More...

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable. More...

Protected Types inherited from TCollection
enum	{ kIsOwner = BIT(14) }

Protected Member Functions inherited from TObjArray
Bool_t	BoundsOk (const char *where, Int_t at) const

Int_t	GetAbsLast () const
	Return absolute index to last object in array. More...

void	Init (Int_t s, Int_t lowerBound)
	Initialize a TObjArray. More...

Bool_t	OutOfBoundsError (const char *where, Int_t i) const
	Generate an out-of-bounds error. Always returns false. More...

Protected Member Functions inherited from TSeqCollection
	TSeqCollection ()

virtual void	Changed ()

Protected Member Functions inherited from TCollection
	TCollection ()

virtual const char *	GetCollectionEntryName (TObject *entry) const
	For given collection entry return the string that is used to identify the object and, potentially, perform wildcard/regexp filtering on. More...

virtual void	PrintCollectionEntry (TObject entry, Option_t option, Int_t recurse) const
	Print the collection entry. More...

virtual void	PrintCollectionHeader (Option_t *option) const
	Print the collection header. More...

Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected). More...

void	MakeZombie ()

#include <TClonesArray.h>

Inheritance diagram for TClonesArray:

[legend]

Member Enumeration Documentation

◆ anonymous enum

anonymous enum

Saved copies of pointers to objects.

Enumerator
kForgetBits
kNoSplit
kBypassStreamer

Definition at line 39 of file TClonesArray.h.

Constructor & Destructor Documentation

◆ TClonesArray() [1/4]

TClonesArray::TClonesArray ( )

Default Constructor.

Definition at line 159 of file TClonesArray.cxx.

◆ TClonesArray() [2/4]

TClonesArray::TClonesArray	(	const char *	classname,
		Int_t	s = `1000`,
		Bool_t	call_dtor = `kFALSE`
	)

Create an array of clone objects of classname.

The class must inherit from TObject. The second argument s indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

The third argument is not used anymore and only there for backward compatibility reasons.

Definition at line 175 of file TClonesArray.cxx.

◆ TClonesArray() [3/4]

TClonesArray::TClonesArray	(	const TClass *	cl,
		Int_t	s = `1000`,
		Bool_t	call_dtor = `kFALSE`
	)

Create an array of clone objects of class cl.

The class must inherit from TObject. The second argument, s, indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

The third argument is not used anymore and only there for backward compatibility reasons.

Definition at line 191 of file TClonesArray.cxx.

◆ TClonesArray() [4/4]

TClonesArray::TClonesArray ( const TClonesArray & tc )

Copy ctor.

Definition at line 200 of file TClonesArray.cxx.

◆ ~TClonesArray()

TClonesArray::~TClonesArray ( )

virtual

Delete a clones array.

Definition at line 252 of file TClonesArray.cxx.

Member Function Documentation

◆ AbsorbObjects() [1/2]

void TClonesArray::AbsorbObjects ( TClonesArray * tc )

Directly move the object pointers from tc without cloning (copying).

This TClonesArray takes over ownership of all of tc's object pointers. The tc array is left empty upon return.

Definition at line 931 of file TClonesArray.cxx.

◆ AbsorbObjects() [2/2]

void TClonesArray::AbsorbObjects	(	TClonesArray *	tc,
		Int_t	idx1,
		Int_t	idx2
	)

Directly move the range of object pointers from tc without cloning (copying).

This TClonesArray takes over ownership of all of tc's object pointers from idx1 to idx2. The tc array is re-arranged by return.

Definition at line 944 of file TClonesArray.cxx.

◆ AddAfter()

void TClonesArray::AddAfter	(	const TObject *	after,
		TObject *	obj
	)

inlinevirtual

Add object in the slot after object after.

If after=0 add object in the last empty slot. Note that this will overwrite any object that might have already been in this slot. For insertion semantics use either a TList or a TOrdCollection.

Reimplemented from TObjArray.

Definition at line 65 of file TClonesArray.h.

◆ AddAt()

void TClonesArray::AddAt	(	TObject *	obj,
		Int_t	idx
	)

inlinevirtual

Add object at position ids.

Give an error when idx is out of bounds (i.e. the array is not expanded).

Reimplemented from TObjArray.

Definition at line 62 of file TClonesArray.h.

◆ AddAtAndExpand()

void TClonesArray::AddAtAndExpand	(	TObject *	obj,
		Int_t	idx
	)

inlinevirtual

Add object at position idx.

If idx is larger than the current size of the array, expand the array (double its size).

Reimplemented from TObjArray.

Definition at line 63 of file TClonesArray.h.

◆ AddAtFree()

Int_t TClonesArray::AddAtFree ( TObject * obj )

inlinevirtual

Return the position of the new object.

Find the first empty cell or AddLast if there is no empty cell

Reimplemented from TObjArray.

Definition at line 64 of file TClonesArray.h.

◆ AddBefore()

void TClonesArray::AddBefore	(	const TObject *	before,
		TObject *	obj
	)

inlinevirtual

Add object in the slot before object before.

If before=0 add object in the first slot. Note that this will overwrite any object that might have already been in this slot. For insertion semantics use either a TList or a TOrdCollection.

Reimplemented from TObjArray.

Definition at line 66 of file TClonesArray.h.

◆ AddFirst()

void TClonesArray::AddFirst ( TObject * obj )

inlinevirtual

Add object in the first slot of the array.

This will overwrite the first element that might have been there. To have insertion semantics use either a TList or a TOrdCollection.

Reimplemented from TObjArray.

Definition at line 60 of file TClonesArray.h.

◆ AddLast()

void TClonesArray::AddLast ( TObject * obj )

inlinevirtual

Add object in the next empty slot in the array.

Expand the array if necessary.

Reimplemented from TObjArray.

Definition at line 61 of file TClonesArray.h.

◆ AddrAt()

TObject * TClonesArray::AddrAt ( Int_t idx )

inline

Definition at line 90 of file TClonesArray.h.

◆ BypassStreamer()

void TClonesArray::BypassStreamer ( Bool_t bypass = kTRUE )

When the kBypassStreamer bit is set, the automatically generated Streamer can call directly TClass::WriteBuffer.

Bypassing the Streamer improves the performance when writing/reading the objects in the TClonesArray. However there is a drawback: When a TClonesArray is written with split=0 bypassing the Streamer, the StreamerInfo of the class in the array being optimized, one cannot use later the TClonesArray with split>0. For example, there is a problem with the following scenario:

A class Foo has a TClonesArray of Bar objects
The Foo object is written with split=0 to Tree T1. In this case the StreamerInfo for the class Bar is created in optimized mode in such a way that data members of the same type are written as an array improving the I/O performance.
In a new program, T1 is read and a new Tree T2 is created with the object Foo in split>1
When the T2 branch is created, the StreamerInfo for the class Bar is created with no optimization (mandatory for the split mode). The optimized Bar StreamerInfo is going to be used to read the TClonesArray in T1. The result will be Bar objects with data member values not in the right sequence. The solution to this problem is to call BypassStreamer(kFALSE) for the TClonesArray. In this case, the normal Bar::Streamer function will be called. The Bar::Streamer function works OK independently if the Bar StreamerInfo had been generated in optimized mode or not.

Definition at line 292 of file TClonesArray.cxx.

◆ CanBypassStreamer()

Bool_t TClonesArray::CanBypassStreamer ( ) const

inline

Definition at line 68 of file TClonesArray.h.

◆ Clear()

void TClonesArray::Clear ( Option_t * option = "" )

virtual

Clear the clones array.

Only use this routine when your objects don't allocate memory since it will not call the object dtors. However, if the class in the TClonesArray implements the function Clear(Option_t *option) and if option = "C" the function Clear() is called for all objects in the array. In the function Clear(), one can delete objects or dynamic arrays allocated in the class. This procedure is much faster than calling TClonesArray::Delete(). When the option starts with "C+", eg "C+xyz" the objects in the array are in turn cleared with the option "xyz"

Reimplemented from TObjArray.

Definition at line 391 of file TClonesArray.cxx.

◆ Compress()

void TClonesArray::Compress ( )

virtual

Remove empty slots from array.

Reimplemented from TObjArray.

Definition at line 303 of file TClonesArray.cxx.

◆ ConstructedAt() [1/2]

TObject * TClonesArray::ConstructedAt ( Int_t idx )

Get an object at index 'idx' that is guaranteed to have been constructed.

It might be either a freshly allocated object or one that had already been allocated (and assumingly used). In the later case, it is the callers responsibility to insure that the object is returned to a known state, usually by calling the Clear method on the TClonesArray.

Tests to see if the destructor has been called on the object. If so, or if the object has never been constructed the class constructor is called using New(). If not, return a pointer to the correct memory location. This explicitly to deal with TObject classes that allocate memory which will be reset (but not deallocated) in their Clear() functions.

Definition at line 348 of file TClonesArray.cxx.

◆ ConstructedAt() [2/2]

TObject * TClonesArray::ConstructedAt	(	Int_t	idx,
		Option_t *	clear_options
	)

Get an object at index 'idx' that is guaranteed to have been constructed.

It might be either a freshly allocated object or one that had already been allocated (and assumingly used). In the later case, the function Clear will be called and passed the value of 'clear_options'

Tests to see if the destructor has been called on the object. If so, or if the object has never been constructed the class constructor is called using New(). If not, return a pointer to the correct memory location. This explicitly to deal with TObject classes that allocate memory which will be reset (but not deallocated) in their Clear() functions.

Definition at line 370 of file TClonesArray.cxx.

◆ Delete()

void TClonesArray::Delete ( Option_t * option = "" )

virtual

Clear the clones array.

Use this routine when your objects allocate memory (e.g. objects inheriting from TNamed or containing TStrings allocate memory). If not you better use Clear() since if is faster.

Reimplemented from TObjArray.

Definition at line 423 of file TClonesArray.cxx.

◆ Expand()

void TClonesArray::Expand ( Int_t newSize )

virtual

Expand or shrink the array to newSize elements.

Reimplemented from TObjArray.

Definition at line 450 of file TClonesArray.cxx.

◆ ExpandCreate()

void TClonesArray::ExpandCreate ( Int_t n )

virtual

Expand or shrink the array to n elements and create the clone objects by calling their default ctor.

If n is less than the current size the array is shrunk and the allocated space is freed. This routine is typically used to create a clonesarray into which one can directly copy object data without going via the "new (arr[i]) MyObj()" (i.e. the vtbl is already set correctly).

Definition at line 480 of file TClonesArray.cxx.

◆ ExpandCreateFast()

void TClonesArray::ExpandCreateFast ( Int_t n )

virtual

Expand or shrink the array to n elements and create the clone objects by calling their default ctor.

If n is less than the current size the array is shrunk but the allocated space is not freed. This routine is typically used to create a clonesarray into which one can directly copy object data without going via the "new (arr[i]) MyObj()" (i.e. the vtbl is already set correctly). This is a simplified version of ExpandCreate used in the TTree mechanism.

Definition at line 520 of file TClonesArray.cxx.

◆ GetClass()

TClass* TClonesArray::GetClass ( ) const

inline

Definition at line 57 of file TClonesArray.h.

◆ MultiSort()

void TClonesArray::MultiSort	(	Int_t	nTCs,
		TClonesArray **	tcs,
		Int_t	upto = `kMaxInt`
	)

Sort multiple TClonesArrays simultaneously with this array.

If objects in array are sortable (i.e. IsSortable() returns true for all objects) then sort array.

Definition at line 1000 of file TClonesArray.cxx.

◆ New()

TObject * TClonesArray::New ( Int_t idx )

Create an object of type fClass with the default ctor at the specified index.

Returns 0 in case of error.

Definition at line 907 of file TClonesArray.cxx.

◆ operator=()

TClonesArray & TClonesArray::operator= ( const TClonesArray & tc )

Assignment operator.

Definition at line 216 of file TClonesArray.cxx.

◆ operator[]() [1/2]

TObject *& TClonesArray::operator[] ( Int_t idx )

virtual

Return pointer to reserved area in which a new object of clones class can be constructed.

This operator should not be used for lefthand side assignments, like a[2] = xxx. Only like, new (a[2]) myClass, or xxx = a[2]. Of course right hand side usage is only legal after the object has been constructed via the new operator or via the New() method. To remove elements from the clones array use Remove() or RemoveAt().

Reimplemented from TObjArray.

Definition at line 859 of file TClonesArray.cxx.

◆ operator[]() [2/2]

TObject * TClonesArray::operator[] ( Int_t idx ) const

virtual

Return the object at position idx. Returns 0 if idx is out of bounds.

Reimplemented from TObjArray.

Definition at line 893 of file TClonesArray.cxx.

◆ Remove()

TObject * TClonesArray::Remove ( TObject * obj )

virtual

Remove object from array.

Reimplemented from TObjArray.

Definition at line 570 of file TClonesArray.cxx.

◆ RemoveAt()

TObject * TClonesArray::RemoveAt ( Int_t idx )

virtual

Remove object at index idx.

Reimplemented from TObjArray.

Definition at line 546 of file TClonesArray.cxx.

◆ RemoveRange()

void TClonesArray::RemoveRange	(	Int_t	idx1,
		Int_t	idx2
	)

virtual

Remove objects from index idx1 to idx2 included.

Reimplemented from TObjArray.

Definition at line 593 of file TClonesArray.cxx.

◆ SetClass() [1/2]

void TClonesArray::SetClass	(	const char *	classname,
		Int_t	size = `1000`
	)

see TClonesArray::SetClass(const TClass*)

Definition at line 664 of file TClonesArray.cxx.

◆ SetClass() [2/2]

void TClonesArray::SetClass	(	const TClass *	cl,
		Int_t	s = `1000`
	)

Create an array of clone objects of class cl.

The class must inherit from TObject. The second argument s indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

NB: This function should not be called in the TClonesArray is already initialized with a class.

Definition at line 627 of file TClonesArray.cxx.

◆ SetOwner()

void TClonesArray::SetOwner ( Bool_t enable = kTRUE )

virtual

A TClonesArray is always the owner of the object it contains.

However the collection its inherits from (TObjArray) does not. Hence this member function needs to be a nop for TClonesArray.

Reimplemented from TCollection.

Definition at line 675 of file TClonesArray.cxx.

◆ Sort()

void TClonesArray::Sort ( Int_t upto = kMaxInt )

virtual

If objects in array are sortable (i.e.

IsSortable() returns true for all objects) then sort array.

Reimplemented from TObjArray.

Definition at line 684 of file TClonesArray.cxx.

Member Data Documentation

◆ fClass

TClass* TClonesArray::fClass

protected

Definition at line 35 of file TClonesArray.h.

◆ fKeep

TObjArray* TClonesArray::fKeep

protected

Pointer to the class of the elements.

Definition at line 36 of file TClonesArray.h.

The documentation for this class was generated from the following files:

core/cont/inc/TClonesArray.h
core/cont/src/TClonesArray.cxx

NOTE 1

NOTE 2

Public Types

Public Member Functions

Protected Attributes

Additional Inherited Members

Member Enumeration Documentation

◆ anonymous enum

Constructor & Destructor Documentation

◆ TClonesArray() [1/4]

◆ TClonesArray() [2/4]

◆ TClonesArray() [3/4]

◆ TClonesArray() [4/4]

◆ ~TClonesArray()

Member Function Documentation

◆ AbsorbObjects() [1/2]

◆ AbsorbObjects() [2/2]

◆ AddAfter()

◆ AddAt()

◆ AddAtAndExpand()

◆ AddAtFree()

◆ AddBefore()

◆ AddFirst()

◆ AddLast()

◆ AddrAt()

◆ BypassStreamer()

◆ CanBypassStreamer()

◆ Clear()

◆ Compress()

◆ ConstructedAt() [1/2]

◆ ConstructedAt() [2/2]

◆ Delete()

◆ Expand()

◆ ExpandCreate()

◆ ExpandCreateFast()

◆ GetClass()

◆ MultiSort()

◆ New()

◆ operator=()

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ Remove()

◆ RemoveAt()

◆ RemoveRange()

◆ SetClass() [1/2]

◆ SetClass() [2/2]

◆ SetOwner()

◆ Sort()

Member Data Documentation

◆ fClass

◆ fKeep