SDL C++ Window Immediately Closes - c++

Question

#include "SDL/SDL.h"
#include "SDL/SDL_Image.h"
#include <string>
using namespace std;
//Const screen variables
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;
const char* SCREEN_CAPTION = "Pyro";
const float GRAVITY = 9.8; //Metres per second **NEEDS TO BE ADJUSTED BECAUSE IT'S IN METRES, NOT PIXELS**
const int jumpHeight = 10;
//Non-Const variables
bool running = true;
bool isJumping = true;
int jump = 0;
int frame = 0;
int level = 1;
SDL_Event event;
Uint8 *keystate = NULL;
//SDL Surfaces
SDL_Surface *screen = NULL;
SDL_Surface *background = NULL;
SDL_Surface *sprite = NULL;
SDL_Surface *bEnemy[10];
//Structs
typedef struct entity {
int health;
int damage;
SDL_Rect hitbox;
bool evolved;
} playerType, enemyType;
playerType player;
enemyType basicEnemy[10];
//Functions
SDL_Surface *loadImage( std::string filename )
{
SDL_Surface *loadedImage = NULL;
SDL_Surface *optimizedImage = NULL;
loadedImage = IMG_Load( filename.c_str() );
if( loadedImage != NULL )
{
optimizedImage = SDL_DisplayFormatAlpha( loadedImage );
SDL_FreeSurface( loadedImage );
}
return optimizedImage;
}
void applySurface( int x, int y, SDL_Surface* source, SDL_Surface* location )
{
SDL_Rect offset;
offset.x = x;
offset.y = y;
SDL_BlitSurface( source, NULL, location, &offset );
}
//Main Function
int main( int argc, char* argv[] )
{
if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )
{
return 1;
}
screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );
if( screen == NULL )
{
return 1;
}
SDL_WM_SetCaption( SCREEN_CAPTION, NULL );
background = loadImage( "images/background.png" );
sprite = loadImage( "images/player.png" );
SDL_FreeSurface( sprite );
SDL_FreeSurface( background );
while( running )
{
//Main game loop
if( SDL_PollEvent( &event ) )
{
switch( event.type )
{
case SDL_QUIT:
running = false;
break;
case SDL_KEYDOWN:
switch( event.key.keysym.sym )
{
case SDLK_q:
running = false;
break;
}
break;
}
}
keystate = SDL_GetKeyState(NULL);
if( keystate[SDLK_q] ) player.evolved = !player.evolved;
if( keystate[SDLK_UP] )
{
if(isJumping != true)
{
isJumping = true;
}
}
if( keystate[SDLK_LEFT] ) player.hitbox.x -= 1;
if( keystate[SDLK_RIGHT] ) player.hitbox.y += 1;
//Window collision
if( player.hitbox.x < 0 ) {player.hitbox.x = 0;}
else if( player.hitbox.x > SCREEN_WIDTH - player.hitbox.w ) {player.hitbox.x = SCREEN_WIDTH - player.hitbox.w;}
if( player.hitbox.y < 0 ) {player.hitbox.y = 0;}
else if( player.hitbox.y > SCREEN_HEIGHT - player.hitbox.h ) {player.hitbox.y = SCREEN_HEIGHT - player.hitbox.h;}
//Jumping
if( isJumping == true )
{
if(jump >= jumpHeight)
{
jump--;
player.hitbox.y++;
}else {
jump++;
player.hitbox.y--;
}
}
//Updating the screen
applySurface( 0, 0, background, screen );
applySurface( player.hitbox.x, player.hitbox.y, sprite, screen );
if( SDL_Flip( screen ) == -1 )
{
return 1;
}
}
SDL_Quit();
return 0;
}
^ That is the exact code I have. When I run the file it immediately closes. It is compiled with: g++ -o myprogram.exe mysource.cpp -lmingw32 -lSDLmain -lSDL -lSDL_image -static-libgcc -static-libstdc++.
The files I have linked to do exist; they are currently placeholders (background is some random png image I found, and the player is an image of 8-bit mario).
How do I stop my program from closing immediately?

Answer 1

SDL_FreeSurface( sprite );
SDL_FreeSurface( background );
This is where your problem lies.
These lines should appear at the end of the program right before you call SDL_Quit().
Currently, you're blitting freed surfaces onto the window.