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Memory and pointers

The functions to allocate memory, share ownership of objects, grouped by what you want to do. The From column says what a program needs before it can call one:

• built-in: nothing; it is always available.
• std/memory: #import "std/memory", then using memory to call it by its bare name.

Jump to: Allocate and free memory · Read and write memory by address · Copy, fill and swap memory · Share one object between owners · Reach the object behind a SharedPtr · Refer to an object without keeping it alive

Allocate and free memory

Function	What it does	From
Allocate	Reserves a number of bytes and returns a pointer to them, or 0; the bytes are not cleared.	built-in
CAllocate	Reserves memory for a number of elements, set to zero, and returns a pointer or 0.	built-in
Reallocate	Resizes a block, keeping its contents, and returns the new pointer, or 0 on failure.	built-in
Deallocate	Frees memory from Allocate, CAllocate or Reallocate; does nothing for a null pointer.	built-in

Read and write memory by address

Function	What it does	From
Peek	Returns a reference to the value at an address, as a byte or as a given type.	built-in
Poke	Writes a value to an address, as a byte or as a given type.	built-in
SAdd	Returns a pointer to the characters of a string.	built-in

Copy, fill and swap memory

Function	What it does	From
Fb_Memcopy	Copies a number of bytes between two memory areas that do not overlap.	built-in
Fb_Memmove	Copies a number of bytes between two memory areas, even when they overlap.	built-in
fb_MemCopyClear	Copies the first bytes of one area into another and sets the rest to zero.	built-in
Clear	Sets a number of bytes, starting at a variable, to zero or to a given value.	built-in
Swap	Exchanges the values of two variables.	built-in

Share one object between owners

Function	What it does	From
SharedPtr	Holds an object shared by several owners and destroys it when the last one lets go.	std/memory
MakeShared	Creates a default-constructed object and returns the first SharedPtr to it.	std/memory
MakeSharedFrom	Creates a copy of a value on the heap and returns a SharedPtr to it.	std/memory
SharedPtr.UseCount	Returns how many SharedPtr handles share the object.	std/memory
SharedPtr.Reset	Drops this handle's share and leaves it null; the last one out destroys the object.	std/memory

Reach the object behind a SharedPtr

Function	What it does	From
SharedPtr.Ref	Returns a reference to the object; raises an error if the handle is null.	std/memory
SharedPtr.Get	Returns the raw pointer to the object, or 0 if null, without adding an owner.	std/memory
SharedPtr.IsNull	Returns true if the handle owns no object.	std/memory
SpCast	Returns a SharedPtr to a base type that shares ownership with the derived one.	std/memory

Refer to an object without keeping it alive

Function	What it does	From
WeakPtr	Holds a link to a shared object that does not keep it alive, to break cycles.	std/memory
WeakPtr.Lock	Returns a SharedPtr to the object if it still exists, or a null one if not.	std/memory
WeakPtr.Expired	Returns true once the object has been destroyed.	std/memory

See Also

• Smart pointers guide
• Memory functions

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