所以我正在使用Dev-C ++ 5.11和Allegro 4.2为我的计算机科学课做一个游戏，我已经到了项目的最后，我想最终修复一段时间以来一直存在的问题。我的代码使用单个.cpp文件相当长，但是当我尝试将我的函数放在一个单独的文件中时，我会收到一系列“多次定义''在这里首次定义'错误。我在网上看过，大多数有这个问题的人都把他们的.cpp文件包含在他们的主要或类似的东西中，但我没有这样做，也无法弄清楚为什么它不起作用。错误指向我在标头中声明的所有变量（位图以及char数组和整数）。
文件：
asteroidsMain.cpp
functions.cpp
asteroids.h
我也使用数据文件。
主文件：
#include <allegro.h>
#include <alfont.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "asteroids.h"
#include "asteroids_data.h"
//Creating movement timer (also used for typing)
volatile long speed_counterA = 0;
void increment_speed_counterA() {
speed_counterA++;
}
END_OF_FUNCTION(increment_speed_counterA);
//Creating laser timer
volatile long speed_counterB = 0;
void increment_speed_counterB() {
speed_counterB++;
}
END_OF_FUNCTION(increment_speed_counterB);
//Creating asteroid timer
volatile long speed_counterC = 0;
void increment_speed_counterC() {
speed_counterC++;
}
END_OF_FUNCTION(increment_speed_counterC);
int main() {
//Initializations
allegro_init();
alfont_init();
set_color_depth(desktop_color_depth());
set_gfx_mode(GFX_AUTODETECT_WINDOWED, 800, 600, 0, 0);
install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, NULL);
install_keyboard();
install_mouse();
install_timer();
//Movement timer
LOCK_VARIABLE(speed_counterA);
LOCK_FUNCTION(increment_speed_counterA);
install_int_ex(increment_speed_counterA, BPS_TO_TIMER(60));
//Laser firing timer
LOCK_VARIABLE(speed_counterB);
LOCK_FUNCTION(increment_speed_counterB);
install_int_ex(increment_speed_counterB, BPS_TO_TIMER(60));
//Asteroid generation timer
LOCK_VARIABLE(speed_counterC);
LOCK_FUNCTION(increment_speed_counterC);
install_int_ex(increment_speed_counterC, BPS_TO_TIMER(60));
//Randomizing seed
srand(time(0));
//Creating/loading BITMAPs formain game
BITMAP *buffer = create_bitmap(800, 600);
shipStopped = loadImage("shipStopped");
shipMoving = loadImage("shipMoving");
laserSprite = loadImage("laser");
smallAsteroid = loadImage("small_Asteroid");
medAsteroid = loadImage("med_Asteroid");
largeAsteroid = loadImage("large_Asteroid");
//General use variables for screen control
int onScreen = 0, i = 0, j = 0;
bool quit = false;
//Retrieving and sorting scores
numOfScores = getHighs(name, score);
sortHighs(name, score);
//Loads main screen
onScreen = changeScreen(0);
while (!quit) {
//If there was an issue loading datafile, error is returned
if (onScreen == -1) {
return 1;
}
else if (onScreen == 0) {
while (onScreen == 0) {
//Primary check is for quitting program, other buttons lead to separate screens
if ((mouse_b & 1) && mouse_x > 400 - 75 &&
mouse_x < 400 + 75 && mouse_y > 450 && mouse_y < 4505 + quitButton->h) { //For clicking Quit
quit = true;
onScreen = -2;
}
else if ((mouse_b & 1) && mouse_x > 400 - 75 &&
mouse_x < 400 + 75 && mouse_y > 150 && mouse_y < 150 + playButton->h) { //For clicking Play
onScreen = changeScreen(2);
}
else if ((mouse_b & 1) && mouse_x > 400 - 75 &&
mouse_x < 400 + 75 && mouse_y > 250 && mouse_y < 250 + highsButton->h) { //For clicking Highscores
onScreen = changeScreen(3);
}
else if((mouse_b & 1) && mouse_x > 400 - 75 &&
mouse_x < 400 + 75 && mouse_y > 350 && mouse_y < 350 + creditsButton->h) { //For clicking Credits
onScreen = changeScreen(4);
}
}
}
else if (onScreen == 2) { //Difficulty choice screen
if ((mouse_b & 1) && mouse_x > 600 - (playButton->w / 2) &&
mouse_x < 600 + (playButton->w / 2) && mouse_y > 192 && mouse_y < 192 + playButton->h) {
onScreen = changeScreen(1);
}
else if ((mouse_b & 1) && mouse_x > 635 && mouse_x < 775 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Returns to main menu
onScreen = changeScreen(0);
}
}
else if (onScreen == 3) { //Highscore screen
if ((mouse_b & 1) && mouse_x > 635 && mouse_x < 775 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Returns to main menu
onScreen = changeScreen(0);
}
}
else if (onScreen == 4) { //Credit screen
if ((mouse_b & 1) && mouse_x > 635 && mouse_x < 775 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Returns to main menu
onScreen = changeScreen(0);
}
}
else if (onScreen == 51) { //Game over screen
if (points <= score[9]) {
if ((mouse_b & 1) && mouse_x > 25 && mouse_x < 175 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Begins a new game
onScreen = changeScreen(2);
}
else if ((mouse_b & 1) && mouse_x > 635 && mouse_x < 775 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Returns to main menu
onScreen = changeScreen(0);
}
}
else {
if (mouse_b & 1) {
//Adding new highschore to array
score[9] = points;
strcpy(name[9], "");
if (numOfScores < 10) {
numOfScores++;
}
onScreen = changeScreen(52);
}
}
}
else if (onScreen == 52) {
speed_counterA = 0;
int keyEnt = 0, len = 0;
char keyHold;
//Text entering for highscore name, moves to next screen on enter
while (!key[KEY_ENTER]) {
//Preventing multiple printing of same key
while (keypressed() && speed_counterA % 3 == 0) {
//Reading key from keyboard and making it useable
keyEnt = readkey();
keyHold = keyEnt & 0xff;
if (keyHold >= 32 && keyHold <= 126) { //Adding chars to name string
len = strlen(name[9]);
if (len < 19) { //Restricting the number of characters you can enter, beyond this does not save properly
name[9][len] = keyHold;
name[9][len + 1] = '\0';
}
}
else if (key[KEY_BACKSPACE]) { //Deleting if backspace char is pressed
name[9][len] = '\0';
len--;
}
clear_keybuf();
}
//Printing text
textprintf_centre_ex(buffer, font, 400, 300, WHITE, -1, "What is your name: %s", name[9]);
textprintf_centre_ex(buffer, font, 400, 500, WHITE, -1, "** press enter to conitue **");
// Blit the buffer
blit(buffer, screen, 0, 0, 0, 0, 800, 600);
clear(buffer);
}
onScreen = changeScreen(53);
}
else if (onScreen == 53) {
if ((mouse_b & 1) && mouse_x > 25 && mouse_x < 175 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Begins a new game
onScreen = changeScreen(2);
}
else if ((mouse_b & 1) && mouse_x > 635 && mouse_x < 775 &&
mouse_y > 575 - menuButton->h && mouse_y < 575) { //Returns to main menu
onScreen = changeScreen(0);
}
}
else if (onScreen == 1) { //Game screen
//Defining
Laser laser[50];
Asteroid asteroid[10];
//Initializing lasers and asteroids
for (i = 0; i < 50; i++) {
laser[i].pos.x = 0;
laser[i].pos.y = 0;
laser[i].angle = 0;
laser[i].onScreen = false;
}
for (i = 0; i < 10; i++) {
asteroid[i].pos.x = 0;
asteroid[i].pos.y = 0;
asteroid[i].angle = 0;
asteroid[i].onScreen = false;
}
//Game specific variables, reset for every new game
int move = 0, lasers= 0, asteroids = 0;
float angle = 0;
bool collide = false;
points = 0;
//Spawning ship when game screen loads
Coordinate ship;
ship.x = 400 - (shipStopped->w / 2);
ship.y = 300 - (shipStopped->h / 2);
//Reseting game timers
speed_counterA = 0;
speed_counterB = 0;
speed_counterC = 0;
while (onScreen == 1) { //Game screen
while (speed_counterA > 0) {
//Ship movement
if (key[KEY_UP] && key[KEY_RIGHT]){
ship.y -= 3;
ship.x += 3;
angle = 32;
}
else if (key[KEY_UP] && key[KEY_LEFT]){
ship.y -= 3;
ship.x -= 3;
angle = 224;
}
else if (key[KEY_DOWN] && key[KEY_RIGHT]) {
ship.y += 3;
ship.x += 3;
angle = 96;
}
else if (key[KEY_DOWN] && key[KEY_LEFT]) {
ship.y += 3;
ship.x -= 3;
angle = 160;
}
else if (key[KEY_UP]){
ship.y -= 6;
angle = 0;
}
else if (key[KEY_RIGHT]) {
ship.x += 6;
angle = 64;
}
else if (key[KEY_LEFT]) {
ship.x -= 6;
angle = 192;
}
else if (key[KEY_DOWN]) {
ship.y += 6;
angle = 128;
}
//Laser movement
for (i = 0; i < 50; i++) {
laser[i] = moveLaser(laser[i]);
}
//Asteroid movement
for (i = 0; i < 10; i++) {
asteroid[i] = moveAsteroid(asteroid[i]);
}
speed_counterA--;
}
//Key trigger for laser firing, if is first as having timer first
//would cause many hits not to be properly registered especially if
//tapping too fast, this allows firing at will with a fastest firing of every 0.15s
if (key[KEY_SPACE]) {
//Laser firing timer
while (speed_counterB > 9) {
//Laser shooting
laser[lasers] = fireLaser(angle, ship.x, ship.y);
if (lasers >= 49) {
lasers = 0;
}
lasers++;
speed_counterB -= 10;
}
}
//Asteroid spawning counter
while (speed_counterC > 59) { //Spawns an asteroiud every second
//Keeping asteroids within array range
if (asteroids >= 9){
asteroids = 0;
}
//Generating asteroid
asteroid[asteroids] = genAsteroid(1, -1);
asteroids++;
speed_counterC -= 60;
}
//If ship goes out top, it comes in bottom; vice versa
if (ship.y <= 0 - ((shipStopped->h / 2))) {
ship.y += (600);
}
else if (ship.y >= 600 - ((shipStopped->h / 2))) {
ship.y -= (600);
}
//If ship goes out left, it comes in right; vice versa
if (ship.x <= 0 - ((shipStopped->w / 2))) {
ship.x += (800);
}
else if (ship.x >= 800 - ((shipStopped->w / 2))) {
ship.x -= (800);
}
//Drawing lasers
for (i = 0; i < 50; i++) {
if (laser[i].onScreen) {
rotate_sprite(buffer, laserSprite, laser[i].pos.x, laser[i].pos.y, ftofix(laser[i].angle));
}
}
//Drawing ship
if (key[KEY_UP] || key[KEY_DOWN] || key[KEY_LEFT] || key[KEY_RIGHT]) {
rotate_sprite(buffer, shipMoving, ship.x, ship.y, ftofix(angle)); //Ship sprite with engines firing
}
else {
rotate_sprite(buffer, shipStopped, ship.x, ship.y, ftofix(angle)); //Ship sprite no flames
}
//Drawing asteroids
for (i = 0; i < 10; i++) {
if (asteroid[i].onScreen == true) {
//Drawing sprite based on asteroid type
if (asteroid[i].type == 1) { //Large asteroid
draw_sprite(buffer, largeAsteroid, asteroid[i].pos.x, asteroid[i].pos.y);
}
else if (asteroid[i].type == 2) { //Medium asteroid
draw_sprite(buffer, medAsteroid, asteroid[i].pos.x, asteroid[i].pos.y);
}
else if (asteroid[i].type == 3) { //Small asteroid
draw_sprite(buffer, smallAsteroid, asteroid[i].pos.x, asteroid[i].pos.y);
}
}
}
//Checks bb collisions
for (i = 0; i < 50; i++) {
for (j = 0; j < 10; j++) {
if (laser[i].onScreen && asteroid[j].onScreen) {
collide = checkCollision(asteroid[j].type, 0, asteroid[j].pos, laser[i].pos);
if (collide) {
laser[i].onScreen = false;
asteroid[j].onScreen = false;
points += 100 * asteroid[j].type;
//Splitting med or large asteroids into 2 asteroids one type down
if (asteroid[j].type < 3) {
asteroid[asteroids] = splitAsteroid(1, asteroid[j]);
asteroid[j] = splitAsteroid(2, asteroid[j]);
asteroids++;
}
}
}
}
}
//Printing score
textprintf_ex(buffer, font, 10, 5, WHITE, -1, "Score: %d", points);
textprintf_ex(buffer, font, 660, 5, WHITE, -1, "Press esc to quit");
// Blit the buffer
blit(buffer, screen, 0, 0, 0, 0, 800, 600);
clear(buffer);
for (i = 0; i < 10; i++) {
if (asteroid[i].onScreen) {
collide = checkCollision(asteroid[i].type, 1, asteroid[i].pos, ship);
if (collide) {
onScreen = changeScreen(51);
}
}
}
//To leave game screen and return to main menu
if (key[KEY_ESC]) {
onScreen = changeScreen(0);
}
}
}
}
//Freeing memory
destroy_bitmap(playButton);
destroy_bitmap(highsButton);
destroy_bitmap(creditsButton);
destroy_bitmap(quitButton);
destroy_bitmap(shipStopped);
destroy_bitmap(shipMoving);
destroy_bitmap(laserSprite);
destroy_bitmap(smallAsteroid);
destroy_bitmap(medAsteroid);
destroy_bitmap(largeAsteroid);
return 0;
}
END_OF_MAIN()
头文件是：
#ifndef ASTEROIDS_H_
#define ASTEROIDS_H_
#define WHITE makecol(255, 255, 255)
#define BLACK makecol(0, 0, 0)
#include <allegro.h>
#include <alfont.h>
//Made global so size pointers can be used throughout
BITMAP *playButton;
BITMAP *playAgainButton;
BITMAP *highsButton;
BITMAP *creditsButton;
BITMAP *quitButton;
BITMAP *menuButton;
BITMAP *shipStopped;
BITMAP *shipMoving;
BITMAP *laserSprite;
BITMAP *smallAsteroid;
BITMAP *medAsteroid;
BITMAP *largeAsteroid;
//Highscore variables are made global; technically bad,
//but makes simplifies printing greatly
int score[10], numOfScores, points;
char name[10][20];
struct Coordinate {
int x, y;
};
struct Laser {
Coordinate pos;
float angle;
bool onScreen;
};
struct Asteroid {
Coordinate pos;
int type;
int angle;
bool onScreen;
};
int changeScreen(int toLoad);
BITMAP* loadImage(const char image[20]);
int getHighs(char name[][20], int high[]);
void sortHighs(char name[][20], int score[]);
void saveHighs(const char name[][20], const int score[], int numOfScores);
Laser fireLaser(float angle, int ship_x, int ship_y);
Laser moveLaser(Laser laser);
Asteroid genAsteroid(int difficulty, int type);
Asteroid splitAsteroid(int order, Asteroid asteroid);
Asteroid moveAsteroid(Asteroid asteroid);
bool checkCollision(int typeA, int typeB, Coordinate asteroid, Coordinate object);
#endif
函数文件归结为：
#include <allegro.h>
#include <alfont.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "asteroids.h"
#include "asteroids_data.h"
/*~500 lines of functions*/
当我简单地将函数放在main之下时，一切都有效
编译日志的副本：
g++.exe -c asteroidsMain.cpp -o asteroidsMain.o -I"C:/Program Files (x86)/Dev-Cpp/MinGW64/include" -I"C:/Program Files (x86)/Dev-Cpp/MinGW64/x86_64-w64-mingw32/include" -I"C:/Program Files (x86)/Dev-Cpp/MinGW64/lib/gcc/x86_64-w64-mingw32/4.9.2/include" -I"C:/Program Files (x86)/Dev-Cpp/MinGW64/lib/gcc/x86_64-w64-mingw32/4.9.2/include/c++" -I"C:/Program Files (x86)/Dev-Cpp/include" -m32
g++.exe asteroidsMain.o functions.o -o POPE_Greg_Asteroids.exe -L"C:/Program Files (x86)/Dev-Cpp/MinGW64/x86_64-w64-mingw32/lib32" -L"C:/Program Files (x86)/Dev-Cpp/lib" -lalfont -lalleg -m32
functions.o:functions.cpp:(.bss+0x0): multiple definition of `playButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x0): first defined here
functions.o:functions.cpp:(.bss+0x4): multiple definition of `playAgainButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x4): first defined here
functions.o:functions.cpp:(.bss+0x8): multiple definition of `highsButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x8): first defined here
functions.o:functions.cpp:(.bss+0xc): multiple definition of `creditsButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0xc): first defined here
functions.o:functions.cpp:(.bss+0x10): multiple definition of `quitButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x10): first defined here
functions.o:functions.cpp:(.bss+0x14): multiple definition of `menuButton'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x14): first defined here
functions.o:functions.cpp:(.bss+0x18): multiple definition of `shipStopped'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x18): first defined here
functions.o:functions.cpp:(.bss+0x1c): multiple definition of `shipMoving'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x1c): first defined here
functions.o:functions.cpp:(.bss+0x20): multiple definition of `laserSprite'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x20): first defined here
functions.o:functions.cpp:(.bss+0x24): multiple definition of `smallAsteroid'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x24): first defined here
functions.o:functions.cpp:(.bss+0x28): multiple definition of `medAsteroid'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x28): first defined here
functions.o:functions.cpp:(.bss+0x2c): multiple definition of `largeAsteroid'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x2c): first defined here
functions.o:functions.cpp:(.bss+0x40): multiple definition of `score'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x40): first defined here
functions.o:functions.cpp:(.bss+0x68): multiple definition of `numOfScores'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x68): first defined here
functions.o:functions.cpp:(.bss+0x6c): multiple definition of `points'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x6c): first defined here
functions.o:functions.cpp:(.bss+0x80): multiple definition of `name'
asteroidsMain.o:asteroidsMain.cpp:(.bss+0x80): first defined here
collect2.exe: error: ld returned 1 exit status
C:\Users\Greg\Documents\Asteroids B\Makefile.win:25: recipe for target 'POPE_Greg_Asteroids.exe' failed
mingw32-make.exe: *** [POPE_Greg_Asteroids.exe] Error 1
标头中声明的变量需要标记为extern并在单独的源文件中进行镜像。如果每个源文件都包含您的标头，则不同文件中将存在多个相同对象的定义，并且链接时将发生重新定义错误。
在同一个项目中添加这些文件。