Thread: SDL movement

Now I am trying to get the image to just move off center a little bit by using differant x and y values. But when I run this program the image move off screen in increments. Ironically this is the effect I wanted but, I didn't think I was ready so i was just trying to move image a little bit off center not have it keep moving. So here is my code the problem is that the images keeps moving rather than just blitting onto the screen a bit off center. Not any where in the code do I modify xpos or ypos, that I can tell, so I Dont see why when ever I redraw the screen the image moves.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include "SDL.h"
using namespace std;

SDL_Surface *scrn1, *back;
int misc;
int xpos=2;
int ypos=1;


int InitSDL();
int Setscreenvidmode();
int Blitscreen(SDL_Surface *scrn, SDL_Surface *scrnn);
int SwitchLoadImg(SDL_Surface *scrn,int imgnum);



int main(int argc, char*argv[]){
    
    int imgnum=1,done=0;
    
    InitSDL();
    atexit(SDL_Quit);
    Setscreenvidmode();
    SwitchLoadImg(scrn1,imgnum);
while(done == 0)
{
    Blitscreen(scrn1,back);
    
    if (imgnum>4){imgnum=1;}
    
    SDL_Event event;

    while ( SDL_PollEvent(&event) )
    {
      if ( event.type == SDL_QUIT )  {  done = 1;  }

      if ( event.type == SDL_KEYDOWN )
      {
        if ( event.key.keysym.sym == SDLK_ESCAPE ) { done = 1; }
        if ( event.key.keysym.sym == SDLK_n) {SwitchLoadImg(scrn1,++imgnum);}
      }
    }
    
  


}}//////////////////////////////////////////END OF MAIN//////////////////////

int InitSDL() {
    if ((SDL_Init(SDL_INIT_VIDEO||SDL_INIT_AUDIO))<0){
        cout<<SDL_GetError();
    }
};

int Setscreenvidmode(){
    scrn1 = SDL_SetVideoMode(500,380,32,SDL_SWSURFACE||SDL_DOUBLEBUF);
    back = SDL_SetVideoMode(500,380,32,SDL_SWSURFACE||SDL_DOUBLEBUF);    
};

int Blitscreen(SDL_Surface *scrnn, SDL_Surface *scrn){
    SDL_Rect trect;
    trect.x=xpos;
    trect.y=ypos;
    SDL_BlitSurface(scrnn,NULL,scrn,&trect);
    SDL_Flip(scrn);
};    
    
int SwitchLoadImg(SDL_Surface *scrn,int imgnum){
    SDL_Surface *temp;
    switch (imgnum){
        case 1:
            temp = SDL_LoadBMP("Pic1.bmp");
            break;
        case 2:
            temp = SDL_LoadBMP("Pic2.bmp");
            break;
        case 3:
            temp = SDL_LoadBMP("Pic3.bmp");
            break;
        case 4:
            temp = SDL_LoadBMP("Pic4.bmp");
            break;
        default:
            temp = SDL_LoadBMP("Pic1.bmp");
            break;
    }
    SDL_BlitSurface(temp,NULL,scrn,NULL);
};