我目前正在为用C++实现的tictactoe的AI工作，目前我的进展正在进行中。在我的代码中，我有一个看起来像这样的结构。
struct Board {
int config[3][3];
Board ** nextboards;
};
void addPossibleMoves(Board *** board, bool xplayer) {
Board * newboard = (Board *)malloc(sizeof(Board));
Board * another = (Board *)malloc(sizeof(Board));
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
newboard -> config[i][j] = compare[i][j];
}
}
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
another -> config[i][j] = compare[i][j];
}
}
Board ***temp = (Board ***)realloc(board, 2*sizeof(Board));
temp = board;
**board = newboard;
printBoard( **board);
}
**board并插入两个节点以测试其是否有效。但是，当代码运行realloc函数时，它将暂停并返回不为零的值。有人可以告诉我我在做什么错。这是我的主要功能。
int main() {
bool xplayer = true;
Board * startboard = (Board *)malloc(sizeof(Board));
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
startboard -> config[i][j] = compare[i][j];
}
}
startboard -> nextboards = (Board **)malloc(sizeof(Board));
addPossibleMoves( & startboard -> nextboards, xplayer);
printBoard( *(startboard -> nextboards));
}
最佳答案
我按照我认为的样子重写了您的代码。我完全保留了您应该执行什么代码的逻辑。我还保留了您处理内存的低级malloc / realloc / free方法。我的代码仍然具有此三重指针***，向您展示如何使用它。同样，在使用free分配之后，您以后也忘记了malloc内存，您应该始终释放分配的那些指针!
在真正的C++代码中，您应该使用new / delete / delete[]代替malloc / free。我认为，即使使用new / delete也不是一个好习惯，最好使用已经为您完成所有内存管理的那些结构，例如std::vector，请参见我的第二个解决方案示例，而不是保持简单的指针和手动删除它们，最好使用std::shared_ptr这样的智能指针。
下面的第一个代码基本上是您的代码，但有所改进。
Try it online!
#include <cstdlib>
#include <cstdio>
struct Board {
int config[3][3];
Board ** nextboards;
};
void freeNextBoards(Board ** nextboards) {
Board ** cur = nextboards;
while (*cur) {
freeNextBoards((*cur)->nextboards);
++cur;
}
nextboards[0] = 0;
}
void freeBoard(Board * board) {
freeNextBoards(board->nextboards);
}
void resizeNextBoards(Board *** pnextboards, int cnt) {
*pnextboards = (Board **)realloc(*pnextboards, cnt * sizeof(Board*));
}
Board * createBoard() {
Board * board = (Board *)malloc(sizeof(Board));
board->nextboards = (Board **)malloc(1 * sizeof(Board*));
board->nextboards[0] = 0;
return board;
}
void printRepStr(char const * s, int cnt = 1) {
for (int j = 0; j < cnt; ++j)
printf("%s", s);
}
void printBoard(Board * board, int indent = 0) {
for (int i = 0; i < 3; ++i) {
printRepStr(" ", indent);
for (int j = 0; j < 3; ++j)
printf("%02d ", board->config[i][j]);
printf("\n");
}
printRepStr(" ", indent);
printRepStr("-", 3 * 3 - 1);
printf("\n");
Board ** cur = board->nextboards;
while (*cur) {
printBoard(*cur, indent + 4);
++cur;
}
}
void addPossibleMoves(Board *** pnextboards, bool xplayer) {
Board * newboard = createBoard();
Board * another = createBoard();
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
newboard->config[i][j] = 2 * (i + j); // compare[i][j];
}
}
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
another->config[i][j] = 3 * (i + j); // compare[i][j];
}
}
freeNextBoards(*pnextboards);
resizeNextBoards(pnextboards, 3);
(*pnextboards)[0] = newboard;
(*pnextboards)[1] = another;
(*pnextboards)[2] = 0;
}
int main() {
bool xplayer = true;
Board * startboard = createBoard();
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
startboard->config[i][j] = 1 * (i + j); // compare[i][j];
}
}
addPossibleMoves(&startboard->nextboards, xplayer);
addPossibleMoves(&startboard->nextboards[0]->nextboards, xplayer);
printBoard(startboard);
freeBoard(startboard);
return 0;
}
00 01 02
01 02 03
02 03 04
--------
00 02 04
02 04 06
04 06 08
--------
00 02 04
02 04 06
04 06 08
--------
00 03 06
03 06 09
06 09 12
--------
00 03 06
03 06 09
06 09 12
--------
std::vector来自动管理内存，对于config的普通2D数组，我使用std::array，将文本输出到控制台，我使用了std::cout，还用于捕获异常我使用了try / catch和std::exception。您可以看到，在下面的基于 vector 的代码中，您根本不需要对
malloc / realloc / free进行任何工作，因为您始终可以忘记分配后释放某些内容，因此所有操作都是在 vector 代码内自动完成的。Try it online!
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <array>
#include <stdexcept>
#include <iostream>
#include <iomanip>
using namespace std;
struct Board {
array<array<int, 3>, 3> config = {};
vector<Board> nextboards;
};
void printRepStr(char const * s, size_t cnt = 1) {
for (size_t j = 0; j < cnt; ++j)
cout << s;
}
void printBoard(Board const & board, size_t indent = 0) {
for (size_t i = 0; i < board.config.size(); ++i) {
printRepStr(" ", indent);
for (int j = 0; j < board.config[i].size(); ++j)
cout << setfill(' ') << setw(2) << board.config[i][j] << " ";
cout << endl;
}
printRepStr(" ", indent);
printRepStr("-", board.config[0].size() * 3 - 1);
cout << endl;
for (auto const & cur: board.nextboards)
printBoard(cur, indent + 4);
}
void addPossibleMoves(vector<Board> & pnextboards, bool xplayer) {
Board newboard, another;
for (size_t i = 0; i < newboard.config.size(); ++i)
for (int j = 0; j < newboard.config[i].size(); ++j)
newboard.config[i][j] = 2 * (i + j); // compare[i][j];
for (size_t i = 0; i < another.config.size(); ++i)
for (int j = 0; j < another.config[i].size(); ++j)
another.config[i][j] = 3 * (i + j); // compare[i][j];
pnextboards.resize(2);
pnextboards[0] = newboard;
pnextboards[1] = another;
}
int main() {
try {
bool xplayer = true;
Board startboard;
for (size_t i = 0; i < startboard.config.size(); ++i)
for (size_t j = 0; j < startboard.config[i].size(); ++j)
startboard.config[i][j] = 1 * (i + j); // compare[i][j];
addPossibleMoves(startboard.nextboards, xplayer);
addPossibleMoves(startboard.nextboards[0].nextboards, xplayer);
printBoard(startboard);
return 0;
} catch (exception const & ex) {
cout << "Exception: " << ex.what() << endl;
} catch (...) {
cout << "Unknown Exception!" << endl;
}
}
关于c++ - 如何重新分配三重指针，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/64691254/