代码使用深度优先搜索算法创建迷宫。代码编译完全正常，但在运行时会产生分段错误。 这是代码：
#include "stdafx.h"
#include <cctype>
#include <ctime>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <vector>
#include "maze2.h"
enum mDirection { UP = 0, DOWN = 1, LEFT = 2, RIGHT = 3 };
//the alrogrithm used for maze generation is the depth first search algorithm
//i followed this as a guide http://www.migapro.com/depth-first-search/
//the link uses arrays but i've tried to use vectors as i believe using arrays was one cause of an issue in the last maze generation code
bool Maze::randDirection(bool firstMove) {
int randAdjSquare;
std::vector<std::vector<int>> unvisAdjSquare; //unvisited adjacent squares
for (int direction = 0; direction < 4; direction++) { //i is the direction
int possible_pmd[2] = { 0, 0 };
if (direction == UP) {
possible_pmd[1] = -1;
}
else if (direction == DOWN) {
possible_pmd[1] = 1;
}
else if (direction == LEFT) {
possible_pmd[0] = -1;
}
else {
possible_pmd[0] = 1;
}
if (algoPath.back()[0] + possible_pmd[0] * 2 >0 && algoPath.back()[0] + possible_pmd[0] * 2 <mazeSize[0] - 1 && algoPath.back()[1] + possible_pmd[1] * 2 > 0 && algoPath.back()[1] + possible_pmd[1] * 2 < mazeSize[1] - 1) {
if (!maze[algoPath.back()[1] + possible_pmd[1] * 2]
[algoPath.back()[0] + possible_pmd[0] * 2][1]) {
std::vector<int> possMove = { possible_pmd[0], possible_pmd[1] };
unvisAdjSquare.push_back(possMove);
}
}
if (unvisAdjSquare.size() > 0) {
randAdjSquare = rand() % unvisAdjSquare.size();
for (int i = 0; i< !firstMove + 1; i++) {
std::vector<int> nextPlace;
nextPlace.push_back(algoPath.back()[0] + unvisAdjSquare[randAdjSquare][0]);
nextPlace.push_back(algoPath.back()[1] + unvisAdjSquare[randAdjSquare][1]);
algoPath.push_back(nextPlace);
maze[algoPath.back()[1]][algoPath.back()[0]][0] = false;
maze[algoPath.back()[1]][algoPath.back()[0]][1] = true;
}
return true;
}
else {
return false;
}
}
return true;
}
void Maze::generateMaze() {
bool firstMove = true;
bool worked = true;
while ((int)algoPath.size() > 1 - firstMove) {
if (!worked) {
algoPath.pop_back();
if (!firstMove && algoPath.size() > 2) {
algoPath.pop_back();
}
else {
break;
}
worked = true;
}
while (worked) {
worked = randDirection(firstMove);
if (firstMove) {
firstMove = false;
}
}
}
}
void Maze::initMaze() { //this function sets up the vector as a grid of the size defined before in the mazeSize variable
for (int i = 0; i < mazeSize[1]; i++) {
for (int j = 0; j <mazeSize[0]; j++) {
bool isEdge; // this bool checks to see if the next square is the edge of the vector, if it is, keep going back until the algorithm is able to move in a new direction
if (i == 0 || i == mazeSize[1] - 1 || j == 0 || j == mazeSize[0] - 1) {
isEdge = true;
}
else {
isEdge = false;
}
std::vector<bool> newCell = { true, isEdge };
if ((int)i + 1 > maze.size()) {
std::vector<std::vector<bool>> newRow = { newCell };
maze.push_back(newRow);
}
else {
maze[i].push_back(newCell);
}
}
}
}
void Maze::printMaze() {
for (int i = 0; i < maze.size(); i++) {
for (int j = 0; j < maze[i].size(); j++) {
if (maze[i][j][0]) {
std::cout << "##";
}
else {
std::cout << " ";
}
}
std::cout << std::endl;
}
}
void Maze::setStartandEnd(bool jeff) {
int axis;
int side;
if (!jeff) {
axis = rand() % 2;
side = rand() % 2;
Maze::startSide = side;
Maze::startAxis = axis;
}
else {
bool done = false;
while (!done) {
axis = rand() % 2;
side = rand() % 2;
if (axis != startAxis || side != startSide) {
done = true;
}
}
}
std::vector<int> place = { 0, 0 };
if (!side) {
place[!axis] = 0;
}
else {
place[!axis] = mazeSize[!axis] - 1;
}
place[axis] = 2 * (rand() % ((mazeSize[axis] + 1) / 2 - 2)) + 1;
if (!jeff) {
algoPath.push_back(place);
}
Maze::maze[place[1]][place[0]][0] = false;
Maze::maze[place[1]][place[0]][1] = true;
}
int main() {
srand(time(NULL));
Maze maze;
maze.initMaze();
maze.setStartandEnd(false);
maze.setStartandEnd(true);
maze.generateMaze();
maze.printMaze();
return 0;
}
这是头文件＆＃34; maze2.h＆＃34;它包含在代码中：
#pragma once
class Maze {
private:
int mazeSize[2];
int startAxis;
int startSide;
std::vector<std::vector<int>> algoPath;
std::vector<std::vector<std::vector<bool>>> maze;
std::vector<int> place;
public:
bool randDirection(bool);
bool validInt(char*);
void generateMaze();
void initMaze();
void printMaze();
void setStartandEnd(bool);
};
我已经通过调试工具运行了它，它一直运行到这一行：
Maze::maze[place[1]][place[0]][0] = false;
我评论了这一点，看看下一行是否会出现同样的问题，而且确实如此。 当线路尝试运行时，调试器给出了这个错误：
Unhandled exception at 0x1008CAB6 (ucrtbased.dll) in maze2.exe: An invalid parameter was passed to a function that considers invalid parameters fatal.
我相信这一点，以及分段错误，表明代码正在尝试分配尚未分配的内存，但我无法弄清楚原因。我已经宣布了一切，所以它应该在记忆中，但我无法弄清楚为什么会发生这种情况。
答案 0 :(得分：1)
正如评论指出的那样，此代码未明确初始化mazeSize的值，因此其值为default initialized到{0,0}
运行时
maze.initMaze();
在main中，Maze :: maze将不会正确初始化（for循环不会运行）。这将导致程序超出范围＆＃34;
时抛出的异常maze.setStartandEnd(false);
尝试访问Maze :: maze中的第一个元素，因为Maze :: maze仍然是空的（大小为0）。