Memory usage blows up

This is a discussion on Memory usage blows up within the C Programming forums, part of the General Programming Boards category; Hi guys, I am using some a piece of code that blows up the memory usage. The function is the ...

  1. #1
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    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!
    ai confini della conoscenza

  2. #2
    Technical Lead QuantumPete's Avatar
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    Quote Originally Posted by violatro View Post
    I guess that the problem is that P is not freed at the end of func
    Yep, that's the problem!
    "No-one else has reported this problem, you're either crazy or a liar" - Dogbert Technical Support
    "Have you tried turning it off and on again?" - The IT Crowd

  3. #3
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    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".
    ai confini della conoscenza

  4. #4
    Captain Crash brewbuck's Avatar
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    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.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  5. #5
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    Thank you very much! In fact the trouble was between malloc() and free()!

    Quote Originally Posted by brewbuck View Post
    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.
    ai confini della conoscenza

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