SDL question

[ccmccm]

Hi,
I am a beginner and I am trying to write a quiz program with an array.
The output should initially show "Question 1". If then I click a button with correct answer, it will increase the score, else decrease the score. But it does not show any "Questions". Please help.
Thanks!

	#include <stdlib.h>
	#include "SDL.h"
	#include "SDL_ttf.h"
	
	// Screen surface
	SDL_Surface *gScreen;
	SDL_Surface* fontSurface;
	SDL_Color fColor;
	SDL_Rect fontRect;
	TTF_Font* font;
	int score=50;
	char buffer [50];
	char question[4][30] = {'Your Question 1','Your Question 2','Your Question 3','Your Question 4'};
	//char choices[4]= {'A. Option A','B. Option B','C. Option C','D. Option D'};
	//char correct_ans[4] = {'B','C','D','A'};
	int index=-1;
	
	//Initialize the font, set to white
	void fontInit(){
			TTF_Init();
			font = TTF_OpenFont("arial.ttf", 28);
			fColor.r = 0;
			fColor.g = 0;
			fColor.b = 255;
	}
	
	//Print the designated string at the specified coordinates
	void printF(char *c, int x, int y){
			fontSurface = TTF_RenderText_Solid(font, c, fColor);
			fontRect.x = x;
			fontRect.y = y;
			SDL_BlitSurface(fontSurface, NULL, gScreen, &fontRect);
	//        SDL_Flip(gScreen);
	}
	
	struct UIState
	{
	  int mousex;
	  int mousey;
	  int mousedown;
	
	  int hotitem;
	  int activeitem;
	} 
	uistate = {0,0,0,0,0};
	
	// Simplified interface to SDL's fillrect call
	void drawrect(int x, int y, int w, int h, int color)
	{
	  SDL_Rect r;
	  r.x = x;
	  r.y = y;
	  r.w = w;
	  r.h = h;
	  SDL_FillRect(gScreen, &r, color);
	}
	
	// Check whether current mouse position is within a rectangle
	int regionhit(int x, int y, int w, int h)
	{
	  if (uistate.mousex < x ||
		uistate.mousey < y ||
		uistate.mousex >= x + w ||
		uistate.mousey >= y + h)
		return 0;
	  return 1;
	}
	
	// Simple button IMGUI widget
	int button(int id, int x, int y)
	{
	  // Check whether the button should be hot
	  if (regionhit(x, y, 220, 48))
	  {
		uistate.hotitem = id;
		if (uistate.activeitem == 0 && uistate.mousedown)
		  uistate.activeitem = id;
	  }
	
	  // Render button 
	  drawrect(x+8, y+8, 220, 48, 0);
	  if (uistate.hotitem == id)
	  {
		if (uistate.activeitem == id)
		{
		  // Button is both 'hot' and 'active'
		  drawrect(x+2, y+2, 220, 48, 0xffffff);
		}
		else
		{
		  // Button is merely 'hot'
		  drawrect(x, y, 220, 48, 0xffffff);
		}
	  }
	  else
	  {
		// button is not hot, but it may be active    
		drawrect(x, y, 220, 48, 0xaaaaaa);
	  }
	
	  // If button is hot and active, but mouse button is not
	  // down, the user must have clicked the button.
	  if (uistate.mousedown == 0 && 
		uistate.hotitem == id && 
		uistate.activeitem == id)
		return 1;
	
	  // Otherwise, no clicky.
	  return 0;
	}
	
	// Prepare for IMGUI code
	void imgui_prepare()
	{
	  uistate.hotitem = 0;
	}
	
	// Finish up after IMGUI code
	void imgui_finish()
	{
	  if (uistate.mousedown == 0)
	  {
		uistate.activeitem = 0;
	  }
	  else
	  {
		if (uistate.activeitem == 0)
		  uistate.activeitem = -1;
	  }
	}
	
	// Rendering function
	void render()
	{ 
	  static int bgcolor = 0x77 ;
	
	  // clear screen
	  drawrect(0,0,640,480,bgcolor);
	
	  //imgui_prepare();
	  
	  //char *q=char(question[index]);
	  printF(question[index], 100, 100);
	  //printF(q, 100, 100);
	 
	  //printF(answer[index], 60, 190);
		 
	  //printF("Your question", 100, 100);
		
	  if (button(1,50,180)) {
		  score =score + 10;
		  exit;
	  }
	  printF("A.Your Answer 1", 60, 190);
	  
	  if (button(2,350,180)){
		  score=score - 10;
	  }
	  printF("B.Your Answer 2", 360, 190);
	  
	  if (button(3,50,280)){
		  score=score - 10;
	  }
	  printF("C.Your Answer 3", 60, 290);
		
	  if (button(4,350,280)){
		  score=score - 10;
	  }
	  printF("D.Your Answer 4", 360, 290);
	  
	  //Score Button
	  button(5,100,350);
	  //convert the score to char and use base 10 to display
	  printF(itoa(score,buffer,10), 110, 360);
	  
	  //Check index
	  //button(6,200,350);
	  printF(itoa(question[index][0],buffer,10), 360, 390);
	  
		  
	  //if (button(3,50,250))
	  //  bgcolor = (SDL_GetTicks() * 0xc0cac01a) | 0x77;
	  
	  //if (button(5,100,400)){
	  //  exit(0);
	  //}
	  
	  imgui_finish();
	
	  // update the screen
		SDL_UpdateRect(gScreen, 0, 0, 640, 480);    
	
	  // don't take all the cpu time
	  SDL_Delay(10); 
	  
	}
	
	
	// Entry point
	int main(int argc, char *argv[])
	{
	  // Initialize SDL's subsystems - in this case, only video.
		if (SDL_Init(SDL_INIT_VIDEO) < 0) 
	  {
			fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
			exit(1);
		}
	
	  // Register SDL_Quit to be called at exit; makes sure things are
	  // cleaned up when we quit.
		atexit(SDL_Quit);
		
	  // Attempt to create a 640x480 window with 32bit pixels.
		gScreen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
	  
	  //Initialize fonts
		fontInit();
	
	  // If we fail, return error.
		if (gScreen == NULL) 
	  {
			fprintf(stderr, "Unable to set up video: %s\n", SDL_GetError());
			exit(1);
		}
	
		
	  // Main loop: loop forever.
		//index=0;
		while (1)
		{
		// Render stuff
			index++;
			render();
						
		// Poll for events, and handle the ones we care about.
			SDL_Event event;
			while (SDL_PollEvent(&event)) 
			{
				switch (event.type) 
				{
		  case SDL_MOUSEMOTION:
			// update mouse position
			uistate.mousex = event.motion.x;
			uistate.mousey = event.motion.y;
			break;
		  case SDL_MOUSEBUTTONDOWN:
			// update button down state if left-clicking
			if (event.button.button == 1)
			  uistate.mousedown = 1;
			break;
		  case SDL_MOUSEBUTTONUP:
			// update button down state if left-clicking
			if (event.button.button == 1)
			  uistate.mousedown = 0;
			break;
				case SDL_KEYUP:                  
			switch (event.key.keysym.sym)
			{
			case SDLK_ESCAPE:
			  // If escape is pressed, return (and thus, quit)
			  return 0;
			}
					break;
				case SDL_QUIT:
					return(0);
				}
			}
			
		}
		return 0;
	}

[Peter87]

Strings should be enclosed in double quotes. Replace all ' with " on line 13.

[ccmccm]

Thanks for your reply.
But It doesn't work by replacing all ' to " .....

[Peter87]

What do you mean with "doesn't work"? Error message?

[ccmccm]

It compiles OK, but the questions do not show up.
Some words are flashing on the question position.

[Peter87]

You are incrementing index in each iteration of the loop so the question text will be different each time, and very soon out of bounds for the question array.

[Fransje]

In your printF() function, you should SDL_FreeSurface( fontSurface ); . Otherwise you'll get memory overflow.

[ccmccm]

Do you mean I should add SDL_FreeSurface(fontSurface); after line 32?

[Fransje]

Exactly. I had the same thing in my SDL game, and after 20 seconds or so it used more than 2GB memory :)

[ccmccm]

It doesn't work even I add that line...
Some things are still flashing
Can somebody use the code and run it in your own PC?

[Peter87]

Did you fix the increment of index? You should probably initialize index to 0 instead of -1.

[ccmccm]

OK thanks!
But now I want to make a main menu to have 3 option buttons.
One is "Start game", another is "Instruction". What should I do and where should I add the codes? If anyone can help modify the codes(I know I am not writing in a good way and the codes seems not working), it is much appreciated.

Here are the codes I am using:

	#include <stdlib.h>
	#include "SDL.h"
	#include "SDL_ttf.h"
	
	// Screen surface
	SDL_Surface *gScreen;
	SDL_Surface* fontSurface;
	SDL_Color fColor;
	SDL_Rect fontRect;
	TTF_Font* font;
	int score=50;
	char buffer [50];
	char question[4][30] = {"Your Question 1","Your Question 2","Your Question 3","Your Question 4"};
	//char choices[4]= {'A. Option A','B. Option B','C. Option C','D. Option D'};
	//char correct_ans[4] = {'B','C','D','A'};
	int index=-1;
	int max_index=3;
	
	//Initialize the font, set to white
	void fontInit(){
			TTF_Init();
			font = TTF_OpenFont("arial.ttf", 28);
			fColor.r = 0;
			fColor.g = 0;
			fColor.b = 255;
	}
	
	//Print the designated string at the specified coordinates
	void printF(char *c, int x, int y){
			fontSurface = TTF_RenderText_Solid(font, c, fColor);
			fontRect.x = x;
			fontRect.y = y;
			SDL_BlitSurface(fontSurface, NULL, gScreen, &fontRect);
			SDL_FreeSurface(fontSurface);
	//        SDL_Flip(gScreen);
	}
	
	struct UIState
	{
	  int mousex;
	  int mousey;
	  int mousedown;
	
	  int hotitem;
	  int activeitem;
	} 
	uistate = {0,0,0,0,0};
	
	// Simplified interface to SDL's fillrect call
	void drawrect(int x, int y, int w, int h, int color)
	{
	  SDL_Rect r;
	  r.x = x;
	  r.y = y;
	  r.w = w;
	  r.h = h;
	  SDL_FillRect(gScreen, &r, color);
	}
	
	// Check whether current mouse position is within a rectangle
	int regionhit(int x, int y, int w, int h)
	{
	  if (uistate.mousex < x ||
		uistate.mousey < y ||
		uistate.mousex >= x + w ||
		uistate.mousey >= y + h)
		return 0;
	  return 1;
	}
	
	// Simple button IMGUI widget
	int button(int id, int x, int y)
	{
	  // Check whether the button should be hot
	  if (regionhit(x, y, 220, 48))
	  {
		uistate.hotitem = id;
		if (uistate.activeitem == 0 && uistate.mousedown)
		  uistate.activeitem = id;
	  }
	
	  // Render button 
	  drawrect(x+8, y+8, 220, 48, 0);
	  if (uistate.hotitem == id)
	  {
		if (uistate.activeitem == id)
		{
		  // Button is both 'hot' and 'active'
		  drawrect(x+2, y+2, 220, 48, 0xffffff);
		}
		else
		{
		  // Button is merely 'hot'
		  drawrect(x, y, 220, 48, 0xffffff);
		}
	  }
	  else
	  {
		// button is not hot, but it may be active    
		drawrect(x, y, 220, 48, 0xaaaaaa);
	  }
	
	  // If button is hot and active, but mouse button is not
	  // down, the user must have clicked the button.
	  if (uistate.mousedown == 0 && 
		uistate.hotitem == id && 
		uistate.activeitem == id)
		return 1;
	
	  // Otherwise, no clicky.
	  return 0;
	}
	
	// Prepare for IMGUI code
	void imgui_prepare()
	{
	  uistate.hotitem = 0;
	}
	
	// Finish up after IMGUI code
	void imgui_finish()
	{
	  if (uistate.mousedown == 0)
	  {
		uistate.activeitem = 0;
	  }
	  else
	  {
		if (uistate.activeitem == 0)
		  uistate.activeitem = -1;
	  }
	}
	
		
	// Rendering function
	void Print_Question()
	{ 
	  static int bgcolor = 0x77 ;
	
	  // clear screen
	  drawrect(0,0,640,480,bgcolor);
	
	  //imgui_prepare();
	  
	  //char *q=char(question[index]);
	  printF(question[index], 100, 100);
	  //printF(q, 100, 100);
	 
	  //printF(answer[index], 60, 190);
		 
	  //printF("Your question", 100, 100);
		
	  if (button(1,50,180)) {
		  score =score + 10;
		  index++;
		  exit;
	  }
	  printF("A.Your Answer 1", 60, 190);
	  
	  if (button(2,350,180)){
		  score=score - 10;
	  }
	  printF("B.Your Answer 2", 360, 190);
	  
	  if (button(3,50,280)){
		  score=score - 10;
	  }
	  printF("C.Your Answer 3", 60, 290);
		
	  if (button(4,350,280)){
		  score=score - 10;
	  }
	  printF("D.Your Answer 4", 360, 290);
	  
	  //Score Button
	  button(5,100,350);
	  //convert the score to char and use base 10 to display
	  printF(itoa(score,buffer,10), 110, 360);
	  
	  //Check index
	  //button(6,200,350);
	  //printF(itoa(question[index][0],buffer,10), 360, 390);
	  
		  
	  //if (button(3,50,250))
	  //  bgcolor = (SDL_GetTicks() * 0xc0cac01a) | 0x77;
	  
	  //if (button(5,100,400)){
	  //  exit(0);
	  //}
	  
	  imgui_finish();
	
	  // update the screen
		SDL_UpdateRect(gScreen, 0, 0, 640, 480);    
	
	  // don't take all the cpu time
	  SDL_Delay(10); 
	  
	}
	
	
	// Entry point
	int main(int argc, char *argv[])
	{
	//The images
      SDL_Surface* bgimg = NULL;
      SDL_Surface* screen = NULL;
		
	  //Load Image
		bgimg = SDL_LoadBMP( "hello.bmp" );	
	
      //Apply to Screen		
		SDL_BlitSurface( bgimg, NULL, screen, NULL );
	  
      //Update Screen
        SDL_Flip( screen );	
	  
	  
	  // Initialize SDL's subsystems - in this case, only video.
		if (SDL_Init(SDL_INIT_VIDEO) < 0) 
	  {
			fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
			exit(1);
		}
	
	  // Register SDL_Quit to be called at exit; makes sure things are
	  // cleaned up when we quit.
		atexit(SDL_Quit);
		
	  // Attempt to create a 640x480 window with 32bit pixels.
		gScreen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
	  
	  	
		
	  //Initialize fonts
		fontInit();
	
	  // If we fail, return error.
		if (gScreen == NULL) 
	  {
			fprintf(stderr, "Unable to set up video: %s\n", SDL_GetError());
			exit(1);
		}

      if (button(2,350,180)){
		  Print_Question();
	  }
	  printF("Enter The Quiz!", 360, 190);
	//	printF("Welcome to this game!",60,200);
	//    printF("Select an Option Below!",70,200);
	  
	    //if (button(3,70,210)){

	
		
	  // Main loop: loop forever.
		index++;
		while (index<=max_index)		
		{
		// Render stuff
			//index++;
			//if (index <=50)
			   //Show_Main_Menu();
			
			//static int bgcolor = 0x77 ;
            //drawrect(0,0,640,480,bgcolor);
	
	            Print_Question();
	        	
			   //Print_Question();
		    //}
						
		// Poll for events, and handle the ones we care about.
			SDL_Event event;
			while (SDL_PollEvent(&event)) 
			{
				switch (event.type) 
				{
		  case SDL_MOUSEMOTION:
			// update mouse position
			uistate.mousex = event.motion.x;
			uistate.mousey = event.motion.y;
			break;
		  case SDL_MOUSEBUTTONDOWN:
			// update button down state if left-clicking
			if (event.button.button == 1)
			  uistate.mousedown = 1;
			break;
		  case SDL_MOUSEBUTTONUP:
			// update button down state if left-clicking
			if (event.button.button == 1)
			  uistate.mousedown = 0;
			break;
				case SDL_KEYUP:                  
			switch (event.key.keysym.sym)
			{
			case SDLK_ESCAPE:
			  // If escape is pressed, return (and thus, quit)
			  return 0;
			}
					break;
				case SDL_QUIT:
					return(0);
				}
			}
			
		}
		return 0;
	}