c programming question

Forum: Other Help Topics
Topic: c programming question
started by: Lii

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Posted by Lii on Feb. 20 2005,07:26

can someone clear something for me, please?
let's say I have the following code:

1:  int main(){
2:  SomeFunction();
3:  return 0;}
4:
5:  int SomeFunction(){
6:  char *ptr;
7:  ptr=(char *)malloc(sizeof(char)*20);
8:  //...do something with ptr
9:  free(ptr);
10: return 0;}

my question is: what happens if I don't use the free(ptr) on line 9? When is the memory deallocated?

-When I return from the SomeFunction function on line 10?
-When I exit the program on line 3?
-Never?

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Posted by clacker on Feb. 20 2005,23:35

Lii, when you leave out the free memory isn't freed, ever.  This is known as a "memory leak."

When you exit the function memory can't be freed by default, what if another function needed that memory and you put the pointer into a global variable?

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Posted by Lii on Feb. 21 2005,06:18

Quote (clacker @ Feb. 20 2005,18:35)

Lii, when you leave out the free memory isn't freed, ever.  This is known as a "memory leak." When you exit the function memory can't be freed by default, what if another function needed that memory and you put the pointer into a global variable?

that's really sad!

thx for your time.

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Posted by clacker on Feb. 21 2005,11:58

not that sad, I mean it causes crashes and all, but memory leaks are all gone when you restart the machine, so it isn't really "never" it's until restart.

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