SDL2/SDL_RWops

Defined in [SDL_rwops.h](https://github.com/libsdl-org/SDL/blob/SDL2/include/SDL_rwops.h), but apps should _only_ `#include "SDL.h"`!

Syntax

typedef struct SDL_RWops
{
    /**
     *  Return the size of the file in this rwops, or -1 if unknown
     */
    Sint64 (SDLCALL * size) (struct SDL_RWops * context);

    /**
     *  Seek to \c offset relative to \c whence, one of stdio's whence values:
     *  RW_SEEK_SET, RW_SEEK_CUR, RW_SEEK_END
     *
     *  \return the final offset in the data stream, or -1 on error.
     */
    Sint64 (SDLCALL * seek) (struct SDL_RWops * context, Sint64 offset,
                             int whence);

    /**
     *  Read up to \c maxnum objects each of size \c size from the data
     *  stream to the area pointed at by \c ptr.
     *
     *  \return the number of objects read, or 0 at error or end of file.
     */
    size_t (SDLCALL * read) (struct SDL_RWops * context, void *ptr,
                             size_t size, size_t maxnum);

    /**
     *  Write exactly \c num objects each of size \c size from the area
     *  pointed at by \c ptr to data stream.
     *
     *  \return the number of objects written, or 0 at error or end of file.
     */
    size_t (SDLCALL * write) (struct SDL_RWops * context, const void *ptr,
                              size_t size, size_t num);

    /**
     *  Close and free an allocated SDL_RWops structure.
     *
     *  \return 0 if successful or -1 on write error when flushing data.
     */
    int (SDLCALL * close) (struct SDL_RWops * context);

    Uint32 type;
    union
    {
#if defined(__ANDROID__)
        struct
        {
            void *asset;
        } androidio;
#elif defined(__WIN32__) || defined(__GDK__)
        struct
        {
            SDL_bool append;
            void *h;
            struct
            {
                void *data;
                size_t size;
                size_t left;
            } buffer;
        } windowsio;
#endif

#ifdef HAVE_STDIO_H
        struct
        {
            SDL_bool autoclose;
            FILE *fp;
        } stdio;
#endif
        struct
        {
            Uint8 *base;
            Uint8 *here;
            Uint8 *stop;
        } mem;
        struct
        {
            void *data1;
            void *data2;
        } unknown;
    } hidden;

} SDL_RWops;

Code Examples

SDL_RWops *io = SDL_RWFromFile("username.txt", "rb");
if (io != NULL) {
    char name[256];
    if (io->read(io, name, sizeof (name), 1) > 0) {
        printf("Hello, %s!\n", name);
    }
    io->close(io);
}

The following is functionally identical to the above example, but uses the recommended macro interface.

SDL_RWops *io = SDL_RWFromFile("username.txt", "rb");
if (io != NULL) {
    char name[256];
    if (SDL_RWread(io, name, sizeof (name), 1) > 0) {
        printf("Hello, %s!\n", name);
    }
    SDL_RWclose(io);
}

Sint64 ()(SDL_RWops )	size	callback that reports stream size; see Remarks
Sint64 ()(SDL_RWops , Sint64, int)	seek	callback that seeks in stream; see Remarks
size_t ()(SDL_RWops , void *, size_t, size_t)	read	callback that reads from the stream; see Remarks
size_t ()(SDL_RWops , const void *, size_t, size_t)	write	callback that writes to the stream; see Remarks
int ()(SDL_RWops )	close	callback that closes the stream; see Remarks
Uint32	type	type of stream; see Remarks
union	hidden	type-specific data; see Remarks

(This is the legacy documentation for stable SDL2, the current stable version; SDL3 is the current development version.)

SDL_RWops

Header File

Syntax

Code Examples

Data Fields