[SDL] First Program: Show Image

This is my first time using SDL.
Install SDL2 for my Linux system:

sudo apt-get install libsdl2-dev libsdl2-image-dev

Now we can test our first SDL program.
This program is pretty simple, I want to show an image as the background of a main window.

1. In Linux system, #include <SDL2/SDL.h> as well as #include <SDL2/SDL_image.h>
2. SDL_Init(SDL_INIT_VIDEO) should be called before initializing the main window.
3. Using SDL_Surface for loading image, SDL_Renderer and SDL_Texture for rendering operation.
4. Free memory.

Code:

#include <iostream>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

using namespace std;
const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;

int main( int argc, char** argv)
{
    if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        cout << " [Error] SDL initialization fail: " << SDL_GetError() << endl;
        exit(1);
    }

    SDL_Window* main_win = SDL_CreateWindow( "Practice_01",
                           SDL_WINDOWPOS_UNDEFINED,
                           SDL_WINDOWPOS_UNDEFINED,
                           SCREEN_WIDTH,
                           SCREEN_HEIGHT,
                           SDL_WINDOW_SHOWN);

    if(main_win == NULL)
    {
        cout << " [Error] Creating main window fail: " << SDL_GetError() << endl;
    }
    SDL_Event event;
    SDL_Surface* bg = IMG_Load(argv[1]);
    SDL_Renderer* renderer = SDL_CreateRenderer(main_win, -1, 0);
    SDL_Texture*  texture  = SDL_CreateTextureFromSurface(renderer, bg);

    while(true)
    {
       SDL_WaitEvent(&event);
       if(event.type == SDL_QUIT)
       {
           break;
       }
       SDL_RenderClear(renderer);
       SDL_RenderCopy(renderer, texture, NULL, NULL);
       SDL_RenderPresent(renderer);
    }

    SDL_DestroyTexture(texture);
    SDL_DestroyRenderer(renderer);
    SDL_FreeSurface(bg);
    SDL_DestroyWindow(main_win);
    SDL_Quit();
    return 0;
}

How to compile:
g++ ../show_img.cpp -w -lSDL2 -lSDL2_image -o ./show_img