C SDL VS Code image is not displaying - c

Question

I have recently started learning game programming in C. I am using a virtual studio code on linux Ubuntu, and image star.png is not displaying on the screen, there are no errors or problems reported by vs code. I have tried reinstalling sdl2-dev and sdl2-image-dev libraries. Maybe it is a problem with SDL, or maybe with my code (it was written in 2013).
The code should draw a white ractangl, which i can move around, on a blue screen and place a star in upper left corner of a window. It does everything except placing a star.
The code: (doesn't show "Cannot dinf star.png!" so I guess it is not that)
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <stdio.h>
typedef struct
{
int x, y;
short life;
char *name;
}Man;
typedef struct
{
//players
Man man;
//image
SDL_Texture *star;
} GameState;
/////////////////////////////////////////////////////////////////////processEvents
int processEvents(SDL_Window *window , GameState *game)
{
SDL_Event event;
int done = 0;
//Check for events
while (SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_WINDOWEVENT_CLOSE:
{
if (window)
{
SDL_DestroyWindow(window);
window = NULL;
done = 1;
}
}
break;
case SDL_KEYDOWN:
{
switch (event.key.keysym.sym)
{
case SDLK_ESCAPE:
done = 1;
break;
}
}
break;
case SDL_QUIT:
done = 1;
break;
}
}
const Uint8 *state = SDL_GetKeyboardState(NULL);
if(state[SDL_SCANCODE_LEFT])
{
game->man.x -= 1;
}
if(state[SDL_SCANCODE_RIGHT])
{
game->man.x += 1;
}
if(state[SDL_SCANCODE_UP])
{
game->man.y -= 1;
}
if(state[SDL_SCANCODE_DOWN])
{
game->man.y += 1;
}
SDL_Delay(10);
return done;
}
/////////////////////////////////////////////////////////////////////////////////////doRender
void doRedner(SDL_Renderer *renderer, GameState *game)
{
SDL_SetRenderDrawColor(renderer , 0, 0, 255, 255); //blue
//screen clean up into blue
SDL_RenderClear(renderer);
//set color
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
SDL_Rect rect = {game->man.x, game->man.y, 80, 80};
SDL_RenderFillRect(renderer, &rect);
//draw a star
SDL_Rect starRect = { 50, 50, 64, 64 };
SDL_RenderCopy(renderer, game->star, NULL, &starRect);
SDL_RenderPresent(renderer);
}
/////////////////////////////////////////////////////////////////////////////////////main funkction
int main(int argc, char *argv[])
{
GameState gameState;
SDL_Window *window = NULL;
SDL_Renderer *renderer = NULL;
SDL_Surface *starSurface = NULL;
SDL_Init(SDL_INIT_VIDEO);
gameState.man.x = 340-40;
gameState.man.y = 240-40;
window = SDL_CreateWindow("Game Widnow",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
640,
480,
0
);
renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
//load image
starSurface = IMG_Load("star.png");
if(starSurface = NULL)
{
printf("Cannot find star.png!\n\n");
SDL_Quit();
return 1;
}
gameState.star = SDL_CreateTextureFromSurface(renderer, starSurface);
SDL_FreeSurface(starSurface);
int done = 0;
while(!done)
{
//check events
done = processEvents(window, &gameState);
//render
doRedner(renderer, &gameState);
}
SDL_Delay(1000);
//exit game and free memory
SDL_DestroyTexture(gameState.star);
//destroy and close window
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
return 0;
}

Answer 1

TL;DR: Your intention is to perform a comparison, but you are using the assignment operator (i.e., =) instead of the comparison operator ==.
The conditional expression in your if statement:
if(starSurface = NULL)
{
...
}
does not check whether starSurface is NULL. The expression starSurface = NULL assigns NULL to starSurface and evaluates to NULL. Therefore, the condition evaluates to false and no error message is displayed.
Instead, you should write (note the double = below):
if (starSurface == NULL)
or just:
if (!starSurface)