Let's break down the error. The source is ld.exe, which is the Linker. The Linker's job is to produce an executable from the various object files, and any libraries. The message mentions C:\Users\DMC\Desktop\SDL\main.exe, so this would be the executable you're building. The message says it cannot open the file due to a permission error. Windows is designed such that any executable file which currently has a running process cannot be modified or deleted. A very likely source of this error is that your program is still running, but you're trying to recompile. There are other ways you could get this error but they are less likely.

How do you avoid this error? The simplest case is where you can see the program's UI Window - simply exit the program, perhaps using the red X in the corner, or hitting the Escape key if you've written your program to close in response to this. It can be handy to implement such a key in Debug mode to speed up development.

You might have a problem if you've introduced a bug in your code where it will not exit when told, or you might be running a program that enters an infinite loop / deadlocks before there is any Window to close.

In this case, if the process is launched from your IDE you may be able to "break into" it using the Debugger to investigate the source of the bug, or simple terminate it if you believe you know what is wrong.

If you cannot see a UI, and your IDE isn't running the process, you can open the Task Manager and try to locate the process there and terminate it. Be careful - if you terminate the wrong process, such as your IDE, you may lose any unsaved work!

If that still doesn't work, there are other possible causes, but as mentioned they are not very likely.

Thanks for reply and I know what you mean....

To me, this reads like you understand the problem and how to solve it in future ... but then you also posted your code, do you have another question?

That program looks like it would quit automatically after about two seconds, provided no errors occur which would cause it to behave otherwise. If you want it to respond to the close window button, or to the escape key, you'd need to add a little input loop.

While in practise an error (e.g. no STARFIELDS.BMP file is found) may either be compensated for by checks in the rest of the code, or may cause a segfault, that you are doing no error checking and recovery means that it is possible that your program invokes undefined behaviour, which means that your process might do unexpected things (such as hang).

Here is your program but with error checking added to the initialisation functions:

#include "SDL.h"
#include <iostream>

//The images
SDL_Surface* hello = NULL;
SDL_Surface* screen = NULL;

int main( int argc, char* args[] )
{
    //Start SDL
    if(SDL_Init( SDL_INIT_EVERYTHING ) < 0) {
        std::cerr << "Failed to initialise SDL: " << SDL_GetError() << std::endl;
        return 1;
    }

    //Set up screen
    screen = SDL_SetVideoMode(640, 320, 32, SDL_SWSURFACE );
    if(!screen) {
        std::cerr << "Failed to set video mode: " << SDL_GetError() << std::endl;
        SDL_Quit();
        return 1;
    }

    //Load image
    hello = SDL_LoadBMP( "STARFIELDS.BMP" );
    if(!hello) {
        std::cerr << "Failed to load image: " << SDL_GetError() << std::endl;
        SDL_Quit();
        return 1;
    }

    //Apply image to screen
    SDL_BlitSurface( hello, NULL, screen, NULL );

    //Update Screen
    SDL_Flip( screen );

    //Pause
    SDL_Delay( 2000 );

    //Free the loaded image
    SDL_FreeSurface( hello );

    //Quit SDL
    SDL_Quit();

    return 0;
}

SDL_BlitSurface() and SDL_Flip() can also fail, so for full correctness you'd need to add similar logic at these points too.