Visual Studio Express 2012's debugger says:
Unhandled exception at 0x00B8147F in PFPJ.exe: 0xC0000005: Access violation
reading location 0x00000008.
Here is the part of the code that the debugger says is the problem:
(Just so you know, width and height are declared globally in main.cpp. All of the functions utilizing these variables are within main.cpp.
SDL_Surface* bmmap = NULL;
bmmap = SDL_LoadBMP( file );
width = bmmap -> w;
height = bmmap -> h;
Specifically the width = bmmap -> w returns the error.
Problem signature:
Problem Event Name: APPCRASH
Application Name: PFPJ.exe
Application Version: 0.0.0.0
Application Timestamp: 51a57a2e
Fault Module Name: PFPJ.exe
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 51a57a2e
Exception Code: c0000005
Exception Offset: 00001838
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789
Every other example I've found for getting width or height out of an SDL_Surface* uses this notation. I don't fully understand what is going on.
What I am certain of is that my own in-built file stream has an output file that shows me where it failed. It fails in a different function when it references width/height in a double for loop. SDL_Surface structs are defined as:
typedef struct SDL_Surface {
Uint32 flags; /* Read-only */
SDL_PixelFormat *format; /* Read-only */
int w, h; /* Read-only */
Uint16 pitch; /* Read-only */
void *pixels; /* Read-write */
SDL_Rect clip_rect; /* Read-only */
int refcount; /* Read-mostly */
} SDL_Surface;
This blows me away. I don't understand where this error comes from, and why this is a problem. It works within the context of the function where I used the -> notation. I've found a number of programs that use surface -> w to get the width, so what's the problem?
(I'm relatively new to C/C++, so any insight is helpful)