I'm using the apply_surfaces function found on lazyfoo.net, and it's been working fine for me. I've been making a pong clone, and it also was working fine, so i decided to break it up into separate header files and what not. But now the function is giving me errors. I have: img.h

#ifndef IMG_H
#define IMG_H
#include "SDL/SDL.h"
#include <time.h>
#include <string>

SDL_Surface *load_image( std::string filename );
void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL );
int getRand(int min, int max); //Nothing to do with images, but who cares.

#endif

img.cpp

#include "SDL/SDL.h"
#include "SDL/SDL_image.h"
#include "img.h"

SDL_Surface *load_image( std::string filename )
{
    //The image that's loaded
    SDL_Surface* loadedImage = NULL;

    //The optimized surface that will be used
    SDL_Surface* optimizedImage = NULL;

    //Load the image
    loadedImage = IMG_Load( filename.c_str() );

    //If the image loaded
    if( loadedImage != NULL )
    {
        //Create an optimized surface
        optimizedImage = SDL_DisplayFormat( loadedImage );

        //Free the old surface
        SDL_FreeSurface( loadedImage );

        //If the surface was optimized
        if( optimizedImage != NULL )
        {
            //Color key surface
            SDL_SetColorKey( optimizedImage, SDL_RLEACCEL | SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) );
        }
    }

    //Return the optimized surface
    return optimizedImage;
}

void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL )
{
    //Holds offsets
    SDL_Rect offset;

    //Get offsets
    offset.x = x;
    offset.y = y;

    //Blit
    SDL_BlitSurface( source, clip, destination, &offset );
}

int getRand(int min, int max)
{
    time_t seconds;
    time(&seconds);
    srand((unsigned int) seconds);
    return (rand() % (max - min + 1) + min)
}

And the error i'm getting is:

Quote: img.cpp:38: error: default argument given for parameter 5 of `void apply_surface(int, int, SDL_Surface*, SDL_Surface*, SDL_Rect*)' img.h:8: error: after previous specification in `void apply_surface(int, int, SDL_Surface*, SDL_Surface*, SDL_Rect*)' :: === Build finished: 2 errors, 0 warnings ===

Can someone help me here?

It's complaining that you gave a default argument to the "clip" parameter in both the header and the cpp. You should only set default arguments in the function's declaration (in the .h), not in its implementation.