Thread: Memory usage blows up

Hi guys,
I am using some a piece of code that blows up the memory usage. The function is the following

Code:

static double ** matrix(int nrh, int nch)
{
    int   i;
    double **m;

    m = (double **) calloc((nrh + 1), sizeof(double *));
    for (i = 0; i <= nrh; i++)
	m[i] = (double*) calloc((nch + 1), sizeof(double));
    return m;
}

and it is used inside another function (let's say "func") that it is called repeatdly in the main program. In particular inside this function the former is used as follows

Code:

double func()
{
int n=1;
double **P
P=matrix(n, n+1);
}

I guess that the problem is that P is not freed at the end of func. I have tried free(P), but of course it did not work. Somebody can help me?
Thank you!

Originally Posted by violatro

I guess that the problem is that P is not freed at the end of func

Yep, that's the problem!

I tried the following inside "func" (hence wothout using the function matrix)

Code:

double func()
{
    int n=1;
    double **P;
    P = (double **) malloc((n + 1)*sizeof(double *));
    for (i = 0; i <= n; i++)
    P[i] = (double*) malloc((n + 2)*sizeof(double));
 
    ....

   for (i = 0; i <= n; i++){ free(P[i]); }
   free(P);
}

but I get the following error " glibc detected".

They really need to change that stupid error message. It leaves you thinking "what the heck is a glibc, and why has one been detected?"

Actually, it means that glibc (the C runtime library) detected a problem of some kind. The full error message probably looked like this:

Code:

*** glibc detected *** the important stuff that you did not post

Whatever that stuff in red is, that's the key to the problem, not the words "glibc detected."

From the code you posted, the free() calls look okay, so I suspect the code in between malloc() and free() is overflowing one or more of those arrays you allocate.

Thank you very much! In fact the trouble was between malloc() and free()!

Originally Posted by brewbuck

They really need to change that stupid error message. It leaves you thinking "what the heck is a glibc, and why has one been detected?"

Actually, it means that glibc (the C runtime library) detected a problem of some kind. The full error message probably looked like this:

Code:

*** glibc detected *** the important stuff that you did not post

Whatever that stuff in red is, that's the key to the problem, not the words "glibc detected."

From the code you posted, the free() calls look okay, so I suspect the code in between malloc() and free() is overflowing one or more of those arrays you allocate.