scope of dynamic variabe after program termination

[babu198649]

hi
a variable is allocated in dynamic memory(using new and is not deleted) and the programs gets terminated .now does the memory allocated will become junk.

int main()
{
	int *i = new int;
}

if the above program is executed it just allocates 4 bytes in heap and the program gets terminated.

does this allocated memory will never be free even after program termination.

[sicarie]

Well think about that - if that were true, then every program ever run would keep its memory, and your disk would require ever-larger space, you could never "delete a file" - you would always need more and more space.

So the compiler is nice enough to take care of this for us. Part of the process the compiler goes through when the program terminates is the freeing of all memory that was used during the program.

[JosAH]

So the compiler is nice enough to take care of this for us. Part of the process the compiler goes through when the program terminates is the freeing of all memory that was used during the program.

A compiler has nothing to do with it; it just delivers compiled object files which
are linked by a linker. The linker produces a certain format file that is condsidered
an executable binary file ('elf' or 'coff' or what have you). When that image is
loaded the instructions are executed; when that process has finished the OS will
remove every trace of it including all memory used by that process. So, yes,
dynamic memory will be lost for the posterity if the process didn't take care of
it itself.

kind regards,

Jos

[sicarie]

Hm, didn't know it was the OS freeing the memory - thanks Jos!

[JosAH]

Hm, didn't know it was the OS freeing the memory - thanks Jos!

Yep, the OS is the guilty one: it manages the 'text' space (where the instructions
are) as well as the stack space and the 'data' space (where your heap is stored
normally). When the process is dead the OS reclaims those spaces again and
simply ruins everything that was in there. All open files and other resourses are
closed as well. Consider the OS the reaper of the dead process.

kind regards,

Jos

[babu198649]

thank u for u r replys

if a variable is newed twice then will the memory be allocated twice.

#include <iostream.h>
int main()
{
    int *i;
    i = new int; //newed first time
    cout<<&*i<<"   ";
    i = new int; //newed second time
    cout<<&*i; 
}

in the above code the variable i is newed twice and the address of newed location is different on both allocations.

how to find a variable is already newed or not.