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Re: losing pointers when concatenating array of structures [message #94051 is a reply to message #94050]

Mon, 09 January 2017 02:10

Heinz Stege
Messages: 189
Registered: January 2003

Senior Member

Well, pointers are tricky sometimes. I will try to explain. The
statement
structarray=struct
in the first loop-path creates a new structure with a new pointer
variable pointing to the _same_ heap variable as struct.array. The
heap variable is _not_ copied.

Undefine is not an IDL routine. I assume you have downloaded this
procedure from the Coyote library. In the second loop path undefine
destroys the struct.array pointer. I.e. it deletes the heap variable
pointed to by struct.array as well as structarray.array.

Your fix with temporary(struct) moves the structure from struct to
structarray. The undefine procedure can't delete the heap variable
anymore, because struct is undefined at that time.

I'm not sure, that I use the right terms in my explanation. I hope, it
gets clear for you yet.

Heinz

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[Message index]

		losing pointers when concatenating array of structures By: MarioIncandenza on Sun, 08 January 2017 22:35
		Re: losing pointers when concatenating array of structures By: Heinz Stege on Mon, 09 January 2017 02:10
		Re: losing pointers when concatenating array of structures By: MarioIncandenza on Mon, 09 January 2017 08:44
		Re: losing pointers when concatenating array of structures By: Jim Pendleton on Mon, 09 January 2017 11:05
		Re: losing pointers when concatenating array of structures By: Heinz Stege on Mon, 09 January 2017 12:33

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