Thread: need help with malloc-free

this is my code :

Code:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define JUMLAH 1000000
#define ISI     100

typedef struct _dodol
{
        char *string;
} dodol;

void testing(void)
{
	dodol **abc = (dodol**)malloc( JUMLAH * sizeof(dodol*) );
	memset(abc, 0, JUMLAH * sizeof(dodol*));
        int i;
        char a[10];

        for(i=0; i<JUMLAH; i++) {
                abc[i] = (dodol*)malloc(sizeof(dodol));
		abc[i]->string = strdup("HALLLLLLLLLLOOOOOOOOOOOO");
        }

        for(i=0; i<JUMLAH; i++) {
		free( abc[i]->string );
                free( abc[i] );
        }
        free(abc);
}

int main()
{
	int i, j;
	char a[10];

	printf("ready to insert\n");
        scanf("%s",a);

	j=1;
	for(i=0; i<j; i++)
		testing();

	
 	printf("done free\n");
        scanf("%s",a);

        return 0;
}

If i run that code, it will be memory leak.
But if i change j>1 (testing() running more than 1 time), the memory is cooled down.
Whats wrong? >.<

Originally Posted by zacs7

Wow, you're allocating a lot of memory... not that it matters, but consider downsizing the test data.

* Don't cast malloc, see the FAQ
* Check if doesn't malloc fail before continuing, it returns NULL if it does.
* testing() will only run once as it is.
* What exactly are you trying to do? You could allocate an array of char * pointers... which point to strings which you also allocate.

what i'm trying to do is to test why after i run testing() for 1 time, the memory is not going down (i use top to see my memory). It's supposed to be freed.
But if i run testing() more than 1 time (try to change j>1), the memory is freed like it supposed to be.

Thx

Originally Posted by sleith

If i run that code, it will be memory leak.
But if i change j>1 (testing() running more than 1 time), the memory is cooled down.
Whats wrong? >.<

Nothing is wrong. Just because you free() some memory does NOT mean it is returned to the system. It just makes it available for future allocation by malloc().

Originally Posted by brewbuck

Nothing is wrong. Just because you free() some memory does NOT mean it is returned to the system. It just makes it available for future allocation by malloc().

Hm..ok2 i undestand now. Thx