Button1 = *Board[0][0];
Pointing to an Array Element
Author
I figured out that the below wouldn't work so I was wondering how would I go about point to an array's element so I could make my Button1 use the value so it could react according to that value, or if possible just make Button1 = Board[0][0]. Thanks in advance.
You declare a pointer, as usual:
You take the address of some variable, as usual:
Adding these together:
This is assuming the elements of "Board" are values, and not themselves pointers.
Type *name = NULL;You take the address of some variable, as usual:
pointer = &variableAdding these together:
// Declared elsewhere...<WhateverType> *Button1 = 0;// Pointing at array element.Button1 = &Board[0][0];This is assuming the elements of "Board" are values, and not themselves pointers.
Author
Uhh... I screwed up big time trying to do what you told me. Hmm.. I guess I should explain to you why I need to know how to do this. I'm trying to make a Tic Tac Toe game using SDL. So face I've been able to display the board and check boxes according to who's turn it is, and I've also made it display who's turn it is.
|Compiler Error:
|=== TicTacToe, Debug ===|
40|error: expected constructor, destructor, or type conversion before '=' token|
||=== Build finished: 1 errors, 0 warnings ===|
Source Code:
|Compiler Error:
|=== TicTacToe, Debug ===|
40|error: expected constructor, destructor, or type conversion before '=' token|
||=== Build finished: 1 errors, 0 warnings ===|
Source Code:
//Player Turnint PlayerTurn = 0;///////////////////////////////int v1,v2,v3,v4,v5,v6,v7,v8,v9;int *Po1 = NULL;Po1 = &Board[0][0]; //Line where compiler says there is a problem./////////////////////////////////The event structureSDL_Event event;//The fontTTF_Font *font = NULL;//The color of the fontSDL_Color textColor = { 19, 198, 245 };class Button{ private: //The attributes of the button SDL_Rect box; //The part of the button sprite sheet that will be shown SDL_Rect* clip; public: //Initialize the variables Button( int x, int y, int w, int h ); //Handles events and set the button's sprite region void handle_events(); //Shows the button on the screen void show();};
The problem is that the line is an assignment statement. This is not allowed outside a function body. You could merge the assignment into the declaration, by initialising like so:
This depends on "Board" being declared also.
Is this a header file?
int * Po1 = &Board[0][0];This depends on "Board" being declared also.
Is this a header file?
You cannot "run code" outside of a function in C++, except to initialize a variable. Initialization is different from "assigning to something immediately after declaring it". It refers to assigning a value while declaring the variable. In your code, you initialize the variable to NULL, and then attempt to assign the real value. In addition to being illegal outside of functions, this is nonsensical: use the real value for the initialization.
Also, what are "int v1,v2,v3,v4,v5,v6,v7,v8,v9;" for? You clearly know about arrays; why not use one for these variables?
Also, what are "int v1,v2,v3,v4,v5,v6,v7,v8,v9;" for? You clearly know about arrays; why not use one for these variables?
Author
Maybe it would be better if I just show you the whole source code so it'll be easier to point out things that could be holding me back.
Full Code:
Full Code:
//The headers#include "SDL/SDL.h"#include "SDL/SDL_image.h"#include "SDL/SDL_ttf.h"#include <string>//Screen attributesconst int SCREEN_WIDTH = 324;const int SCREEN_HEIGHT = 386;const int SCREEN_BPP = 32;//The button states in the sprite sheetconst int CLIP_MOUSEOVER = 0;const int CLIP_MOUSEOUT = 1;const int CLIP_MOUSEDOWN = 2;//The surfacesSDL_Surface *grid = NULL;SDL_Surface *screen = NULL;SDL_Surface *message = NULL;SDL_Surface *message2 = NULL;//SDL grid_tiles RectSDL_Rect clips[3];//Grid Arrayint Board [3][3] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 }};//Player Turnint PlayerTurn = 0;//The event structureSDL_Event event;//The fontTTF_Font *font = NULL;//The color of the fontSDL_Color textColor = { 19, 198, 245 };class Button{ private: //The attributes of the button SDL_Rect box; //The part of the button sprite sheet that will be shown SDL_Rect* clip; public: //Initialize the variables Button( int x, int y, int w, int h ); //Handles events and set the button's sprite region void handle_events(); //Shows the button on the screen void show();};SDL_Surface *load_image( std::string filename ){ //The image that's loaded SDL_Surface* loadedImage = NULL; //The optimized surface that will be used SDL_Surface* optimizedImage = NULL; //Load the image loadedImage = IMG_Load( filename.c_str() ); //If the image loaded if( loadedImage != NULL ) { //Create an optimized surface optimizedImage = SDL_DisplayFormat( loadedImage ); //Free the old surface SDL_FreeSurface( loadedImage ); //If the surface was optimized if( optimizedImage != NULL ) { //Color key surface SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) ); } } //Return the optimized surface return optimizedImage;}void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL ){ //Holds offsets SDL_Rect offset; //Get offsets offset.x = x; offset.y = y; //Blit SDL_BlitSurface( source, clip, destination, &offset );}void set_board(){ clips[ CLIP_MOUSEOVER ].x = 0; clips[ CLIP_MOUSEOVER ].y = 0; clips[ CLIP_MOUSEOVER ].w = 108; clips[ CLIP_MOUSEOVER ].h = 112; clips[ CLIP_MOUSEOUT ].x = 108; clips[ CLIP_MOUSEOUT ].y = 0; clips[ CLIP_MOUSEOUT ].w = 108; clips[ CLIP_MOUSEOUT ].h = 112; clips[ CLIP_MOUSEDOWN ].x = 216; clips[ CLIP_MOUSEDOWN ].y = 0; clips[ CLIP_MOUSEDOWN ].w = 108; clips[ CLIP_MOUSEDOWN ].h = 112;}bool init(){ //Initialize all SDL subsystems if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 ) { return false; } //Set up the screen screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE ); //If there was an error in setting up the screen if( screen == NULL ) { return false; } //Initialize SDL_ttf if( TTF_Init() == -1 ) { return false; } //Set the window caption SDL_WM_SetCaption( "Tic Tac Toe", NULL ); //If everything initialized fine return true;}bool load_files(){ //Load the Tic Tac Toe grid grid = load_image( "images/Grid2.png" ); //Open the font font = TTF_OpenFont( "fonts/mangat.ttf", 32 ); //If there was a problem in loading the grid if( grid == NULL ) { return false; } //If there was an error in loading the font if( font == NULL ) { return false; } //If everything loaded fine return true;}void clean_up(){ //Free the surfaces SDL_FreeSurface( grid ); SDL_FreeSurface( message ); SDL_FreeSurface( message2 ); //Close the font TTF_CloseFont( font ); //Quit SDL_ttf TTF_Quit(); //Quit SDL SDL_Quit();}Button::Button( int x, int y, int w, int h ){ //Set the button's attributes box.x = x; box.y = y; box.w = w; box.h = h; //Set the default sprite clip = &clips[ CLIP_MOUSEOVER ];}void Button::handle_events(){ //The mouse offsets int x = 0, y = 0; //If a mouse button was pressed if( event.type == SDL_MOUSEBUTTONDOWN ) { //If the left mouse button was pressed if( event.button.button == SDL_BUTTON_LEFT ) { //Get the mouse offsets x = event.button.x; y = event.button.y; //If the mouse is over the button if( ( x > box.x ) && ( x < box.x + box.w ) && ( y > box.y ) && ( y < box.y + box.h ) ) { if( clip == &clips[ CLIP_MOUSEOVER ] ) { if( PlayerTurn == 0 ) { //Set the button sprite clip = &clips[ CLIP_MOUSEOUT ]; PlayerTurn++; } else { //Set the button sprite clip = &clips[ CLIP_MOUSEDOWN ]; PlayerTurn--; } } } } }}void Button::show(){ //Show the button apply_surface( box.x, box.y, grid, screen, clip );}int main( int argc, char* args[] ){ //Quit flag bool quit = false; //Initialize if( init() == false ) { return 1; } //Load the files if( load_files() == false ) { return 1; } //Clip the sprite sheet set_board(); //Make the button Button Button1( 0, 0+50, 108, 112 ); Button Button2( 0, 112+50, 108, 112 ); Button Button3( 0, 224+50, 108, 112 ); Button Button4( 108, 0+50, 108, 112 ); Button Button5( 108, 112+50, 108, 112 ); Button Button6( 108, 224+50, 108, 112 ); Button Button7( 216, 0+50, 108, 112 ); Button Button8( 216, 112+50, 108, 112 ); Button Button9( 216, 224+50, 108, 112 ); message = TTF_RenderText_Solid( font, "Player 1's Turn", textColor ); message2 = TTF_RenderText_Solid( font, "Player 2's Turn", textColor ); //If there was an error in rendering the text if( message == NULL ) { return 1; } //If there was an error in rendering the text if( message2 == NULL ) { return 1; } //Update the screen if( SDL_Flip( screen ) == -1 ) { return 1; } //While the user hasn't quit while( quit == false ) { //If there's an event to handle while( SDL_PollEvent( &event ) ) { //Handle button events Button1.handle_events(); Button2.handle_events(); Button3.handle_events(); Button4.handle_events(); Button5.handle_events(); Button6.handle_events(); Button7.handle_events(); Button8.handle_events(); Button9.handle_events(); //If the user has Xed out the window if( event.type == SDL_QUIT ) { //Quit the program quit = true; } } //Fill the screen white SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 0xFF, 0xFF, 0xFF ) ); //Show the button Button1.show(); Button2.show(); Button3.show(); Button4.show(); Button5.show(); Button6.show(); Button7.show(); Button8.show(); Button9.show(); if( PlayerTurn == 0 ) { apply_surface( 22, 0, message, screen ); } else { apply_surface( 22, 0, message2, screen ); } //Update the screen if( SDL_Flip( screen ) == -1 ) { return 1; } } //Clean up clean_up(); return 0;}
Put the buttons into an array. Use arithmetic on the array index to calculate drawing positions. Similarly, you don't need to create the RECTs for the button sprites ahead of time; you can use arithmetic on the CLIP_ value to calculate the x and y position on the fly, and substitute in the width and height from the Button's 'box', so all you really need to remember is the button's state. (And why not use an enum for those values?) To handle_events(), you can just loop through the array.
PlayerTurn shouldn't change until the mouse is *released*, inside the same button that was initially pressed. You should keep track somewhere of which button was selected when the mouse was pressed, and only alter its state until the button is released again. When the mouse is released, if it's inside the original button, you can send "Player wants to move here" logic to whatever code handles the Board contents.
PlayerTurn shouldn't change until the mouse is *released*, inside the same button that was initially pressed. You should keep track somewhere of which button was selected when the mouse was pressed, and only alter its state until the button is released again. When the mouse is released, if it's inside the original button, you can send "Player wants to move here" logic to whatever code handles the Board contents.
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