Displaying the rectangle using a for loop in SDL2 C - c

Question

I'm currently using a for loop to create 4 rectangles along the x-axis. When I run the program the image of the rectangle appears for a few millisecond before it disappears. Can you show me what I have to do in order for the image to display on the screen permanently.
When I create individual rectangles it display's the image without vanishing.
An example will be helpful. Thanks
int main(){
int barrack1_xposition = 167,i=1;
int cnt_barrack=0;
SDL_Window *o = NULL;
SDL_Renderer *r = NULL;
SDL_Rect bar1[4];
SDL_Event e;
SDL_Init(SDL_INIT_VIDEO);
o = SDL_CreateWindow("SPACE INVADERS",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
1024,
800,
SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
r = SDL_CreateRenderer(o, -1,SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
while(i)
{
while(SDL_PollEvent(&e) !=0)
{
if(e.type == SDL_QUIT)
i=0;
}
for(cnt_barrack = 0; cnt_barrack < 4; cnt_barrack++)
{
bar1[cnt_barrack].x=barrack1_xposition;
bar1[cnt_barrack].y=250;
bar1[cnt_barrack].h=50;
bar1[cnt_barrack].w=50;
barrack1_xposition += 200;
}
SDL_SetRenderDrawColor(r,255,255,255,255);
SDL_RenderFillRect(r,&bar1[0]);
SDL_RenderFillRect(r,&bar1[1]);
SDL_RenderFillRect(r,&bar1[2]);
SDL_RenderFillRect(r,&bar1[3]);
SDL_RenderPresent(r);
}
SDL_DestroyWindow(o);
SDL_DestroyRenderer(r);;
SDL_Quit();
}

Answer 1

Your problem caused by the fact you didn't reset barrack1_xposition on each frame, so it keeps going higher and higher. I initially didn't notice that because there was no RenderClear so it seemed to be fine but actually wasn't.
#include "SDL.h"
int main(){
int barrack1_xposition,i=1;
int cnt_barrack=0;
SDL_Window *o = NULL;
SDL_Renderer *r = NULL;
SDL_Rect bar1[4];
SDL_Event e;
SDL_Init(SDL_INIT_VIDEO);
o = SDL_CreateWindow("SPACE INVADERS",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
1024,
800,
SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
r = SDL_CreateRenderer(o, -1,SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
while(i)
{
while(SDL_PollEvent(&e) !=0)
{
if(e.type == SDL_QUIT)
i=0;
}
barrack1_xposition=167;
for(cnt_barrack = 0; cnt_barrack < 4; cnt_barrack++)
{
bar1[cnt_barrack].x=barrack1_xposition;
bar1[cnt_barrack].y=250;
bar1[cnt_barrack].h=50;
bar1[cnt_barrack].w=50;
barrack1_xposition += 200;
}
SDL_SetRenderDrawColor(r,0,0,0,0);
SDL_RenderClear(r);
SDL_SetRenderDrawColor(r,255,255,255,255);
SDL_RenderFillRect(r,&bar1[0]);
SDL_RenderFillRect(r,&bar1[1]);
SDL_RenderFillRect(r,&bar1[2]);
SDL_RenderFillRect(r,&bar1[3]);
SDL_RenderPresent(r);
}
SDL_DestroyWindow(o);
SDL_DestroyRenderer(r);;
SDL_Quit();
return 0;
}