SDL C++ Moving a rectangle automatically - c++

Question

I'm trying to create a smaller game and I need to get a rectangle to move left to right within the window. Note that this is not the fully completed code. Below is a snippet of a created window class and the run function of it.
I can draw the rectangle, and at the moment it's also moving. However, when I'm pressing up/down it'll move to the right as well, but I want it to do it automatically. If I move the for-loop calling movement() outside of while (which I assume it should..?), the rectangle just disappears.
Another thing to note is that movement should be called through the vector pcEnhet, since I'll use it with other sprites later on.
void Spelplan::run() {
SDL_RenderClear(render);
for (PCKomponent* k : pcEnhet)
k->draw();
SDL_RenderPresent(render);
bool spela = true;
while (spela) {
SDL_Event eve;
while (SDL_PollEvent(&eve)) {
switch (eve.type) {
case SDL_QUIT:
spela = false;
break;
case SDL_KEYDOWN:
switch (eve.key.keysym.sym) {
case SDLK_DOWN:
for (PCKomponent* k : pcEnhet)
k->knappNer(eve);
break;
case SDLK_UP:
for (PCKomponent* k : pcEnhet)
k->knappUpp(eve);
break;
}//keysym switch
SDL_RenderClear(render);
for (PCKomponent* k : pcEnhet)
k->draw();
SDL_RenderPresent(render);
}//eve.type switch
for (PCKomponent* k : pcEnhet) {
k->movement();
k->draw();
}
}//while SDL_Poll
}//while spela
}
void Spelare::movement() {
area.x++;
}
void Spelare::draw() {
SDL_RenderCopy(sp->getPlan(), spelareTexture, NULL, &area);
}

Answer 1

Don't do the rendering in while (SDL_PollEvent(&eve)), but in while (spela). Your items have to be moved/drawn not depending on whether the input is being registered.
while (SDL_PollEvent(&eve)) {
...
}
SDL_RenderClear(render);
for (PCKomponent* k : pcEnhet) {
k->movement();
k->draw();
}
SDL_RenderPresent(render);
Remove the "pre-rendering" code you have above the bool spela = true; line, and remember to make your event loop similar to this from now on.
Note that rather than moving all the objects, you could think of them as stationary and move just the camera (viewport), with which you would calculate the absolute coordinates of the objects in their draw function.
And also, pick one from the two:
spela = false; // will render one last frame
break; // ^ will not, and does not require spela variable at all