Problems with libpng

I'm playing around with libpng, but I,m having problems allocating space. Heres what the manual says:

Quote:

---

After you have called png_read_png(), you can retrieve the image data with

row_pointers = png_get_rows(png_ptr, info_ptr);

where row_pointers is an array of pointers to the pixel data for each row:

png_bytep row_pointers[height];

---

Now, if I do this:

Code:

---

        png_bytep row_pointers[height+1]; //? is this right pointer type
        row_pointers = png_get_rows(png_ptr, info_ptr); //Allcoate memory
        png_read_image(png_ptr, row_pointers);                        //Read data

---

I get errors on the second an third row about incompatible assignment/pointer types.

If I do this:

Code:

---

        png_bytep *row_pointers[height+1];  //segfaults here
        *row_pointers = png_get_rows(png_ptr, info_ptr);
        png_read_image(png_ptr,* row_pointers);

---

It compiles but segfaults at the first line. Anyone know what I am meant to be oing with these pointer things here? Cheers.

Well since you can't return an array, it would be just a pointer.
Say

png_bytep *row_pointers = png_get_rows(png_ptr, info_ptr);

IIRC, the examples in libpng show you how all this stuff works.

Quote:

---

png_bytep *row_pointers = png_get_rows(png_ptr, info_ptr);

---

Cheer Salem, I tried this before but got segfaults. I'm doing it a slightly different way now working off an example. Been having internet connection problems today, so I was pretty much stuck with the manpage before. I'm still getting segfaults atm and I'm starting to get the impression that something else would be causing it. For example if I comment out this line:

Code:

---

unsigned long row_bytes, i;

---

My code runs; otherwise it segfaults. wtf?

Classic buffer overrun.
Assign values to those variables, and you should see them being trashed (harmlessly), rather than something else (which is far from harmless).

Yep that was it. All the way at the beggining of my code, but it was easy to fix.