10. Usage of my_malloc and my_free

Try to avoid using malloc and realloc as much as possible and use new and zap(delete). But sometimes you may need to use the "C" style memory allocations in "C++". Use the functions my_malloc() , my_realloc() and my_free(). These functions do proper allocations and initialisations and try to prevent memory problems. Also these functions (in DEBUG mode) can keep track of memory allocated and print total memory usage before and after the program is run. This tells you if there are any memory leaks.

The my_malloc and my_realloc is defined as below. It allocates little more memory (SAFE_MEM = 5) and initializes the space and if it cannot allocate it exits the program. The 'call_check(), remove_ptr()' functions are active only when DEBUG_MEM is defined in makefile and are assigned to ((void)0) i.e. NULL for non-debug production release. They enable the total-memory used tracing.

void *local_my_malloc(size_t size, char fname[], int lineno) 
{
        size_t  tmpii = size + SAFE_MEM;
        void *aa = NULL;
        aa = (void *) malloc(tmpii);
        if (aa == NULL)
                raise_error_exit(MALLOC, VOID_TYPE, fname, lineno);
        memset(aa, 0, tmpii);
        call_check(aa, tmpii, fname, lineno);
        return aa;
}

char *local_my_realloc(char *aa, size_t size, char fname[], int lineno)
{
        remove_ptr(aa, fname, lineno);
        unsigned long tmpjj = 0;
        if (aa) // aa !=  NULL
                tmpjj = strlen(aa);
        unsigned long tmpqq = size + SAFE_MEM;
        size_t  tmpii = sizeof (char) * (tmpqq);
        aa = (char *) realloc(aa, tmpii);
        if (aa == NULL)
                raise_error_exit(REALLOC, CHAR_TYPE, fname, lineno);

        // do not memset memset(aa, 0, tmpii);
        aa[tmpqq-1] = 0;
        unsigned long kk = tmpjj;
        if (tmpjj > tmpqq)
                kk = tmpqq;
        for ( ; kk < tmpqq; kk++)
                aa[kk] = 0;
        call_check(aa, tmpii, fname, lineno);
        return aa;
}

An example on usage of my_malloc and my_free as below:

        char    *aa;
        int     *bb;
        float   *cc;
        aa = (char *) my_malloc(sizeof(char)* 214);
        bb = (int *) my_malloc(sizeof(int) * 10);
        cc = (float *) my_malloc(sizeof(int) * 20);

        aa = my_realloc(aa, sizeof(char) * 34);
        bb = my_realloc(bb, sizeof(int) * 14);
        cc = my_realloc(cc, sizeof(float) * 10);