Thread: Dynamic allocation inside function

File allocate.c:

Code:

void f(double **X, int *A, size_t sz) {

    /* ... */

X = malloc (sz * sizeof(double *));

for (i=0;i<sz;i++) {*X=malloc (A[i]*sizeof (double)); *X++;}

}

int main () {

      double **Y = 0;
      double A[5]={1, 2, 3, 4, 5};
      size_t sz = 5;

       f(Y);

}

% ./allocate
Segmentation fault

Does f() actually allocate space for Y? I'd like to do it inside of a function, if possible. Any suggestions?

Yep! f() allocates space for X; but there are quite a few things wrong with this code snippet.
Function f() takes 3 parameters, yet you are calling it with a single argument inside of main().
Though X and *X point to blocks of storage but *X++ does not and the cause of your segfault.

Thanks. Yeah, I meant

Code:

f(Y, A, sz);

Can you actually allocate space for Y through the call to f(), though? Y is initialized in main() but no space is allocated before f() is called. Does the call actually allocate the space for Y?

As long as f() returns X, which then is made available to Y in main().