k*******3
发帖数: 1909 | 1 下面这个程序来自Data structures and algorithms in C++ by Adam Drozdek
第四章的迷宫（maze）程序。
我的疑问是最后几行main函数里面的Maze().exitMaze();怎么解释，我想不通语法是怎
么样的。
Maze()是调用哪个函数呢？如果是Maze class的Maze() constructor,难道不用先定义
一个Maze 对象吗？
谢谢。
#include
#include
#include
using namespace std;
template
class Stack : public stack {
public:
T pop() {
T tmp = top();
stack::pop();
return tmp;
}
};
class Cell {
public:
Cell(int i = 0, int j = 0) {
x = i; y = j;
}
bool operator== (const Cell& c) const {
return x == c.x && y == c.y;
}
private:
int x, y;
friend class Maze;
};
class Maze {
public:
Maze();
void exitMaze();
private:
Cell currentCell, exitCell, entryCell;
const char exitMarker, entryMarker, visited, passage, wall;
Stack mazeStack;
char **store; // array of strings;
void pushUnvisited(int,int);
int rows, cols;
friend ostream& operator<< (ostream& out, const Maze& maze) {
for (int row = 0; row <= maze.rows+1; row++)
out << maze.store[row] << endl;
out << endl;
return out;
}
};
Maze::Maze() : exitMarker('e'), entryMarker('m'), visited('.'),
passage('0'), wall('1') {
Stack mazeRows;
char str[80], *s;
int col, row = 0;
cout << "Enter a rectangular maze using the following "
<< "characters:\nm - entry\ne - exit\n1 - wall\n0 - passage\n"
<< "Enter one line at at time; end with Ctrl-z:\n";
while (cin >> str) {
row++;
cols = strlen(str);
s = new char[cols+3]; // two more cells for borderline columns;
mazeRows.push(s);
strcpy(s+1,str);
s[0] = s[cols+1] = wall; // fill the borderline cells with 1s;
s[cols+2] = '\0';
if (strchr(s,exitMarker) != 0) {
exitCell.x = row;
exitCell.y = strchr(s,exitMarker) - s;
}
if (strchr(s,entryMarker) != 0) {
entryCell.x = row;
entryCell.y = strchr(s,entryMarker) - s;
}
}
rows = row;
store = new char*[rows+2]; // create a 1D array of pointers;
store[0] = new char[cols+3]; // a borderline row;
for ( ; !mazeRows.empty(); row--) {
store[row] = mazeRows.pop();
}
store[rows+1] = new char[cols+3]; // another borderline row;
store[0][cols+2] = store[rows+1][cols+2] = '\0';
for (col = 0; col <= cols+1; col++) {
store[0][col] = wall; // fill the borderline rows with 1s;
store[rows+1][col] = wall;
}
}
void Maze::pushUnvisited(int row, int col) {
if (store[row][col] == passage || store[row][col] == exitMarker) {
mazeStack.push(Cell(row,col));
}
}
void Maze::exitMaze() {
int row, col;
currentCell = entryCell;
while (!(currentCell == exitCell)) {
row = currentCell.x;
col = currentCell.y;
cout << *this; // print a snapshot;
if (!(currentCell == entryCell))
store[row][col] = visited;
pushUnvisited(row-1,col);
pushUnvisited(row+1,col);
pushUnvisited(row,col-1);
pushUnvisited(row,col+1);
if (mazeStack.empty()) {
cout << *this;
cout << "Failure\n";
return;
}
else currentCell = mazeStack.pop();
}
cout << *this;
cout << "Success\n";
}
int main() {
Maze().exitMaze();
return 0;
} | | p***o
发帖数: 1252 | 2
Somewhat yes.
No, you are creating a temporary one by saying Maze().
Well, it seems the whole piece of code is of bad taste. I don't think
anyone will write C++ like that in production code. Get a better book
from someone that knows how to write C++ programs.
【在 k*******3 的大作中提到】
: 下面这个程序来自Data structures and algorithms in C++ by Adam Drozdek
: 第四章的迷宫（maze）程序。
: 我的疑问是最后几行main函数里面的Maze().exitMaze();怎么解释，我想不通语法是怎
: 么样的。
: Maze()是调用哪个函数呢？如果是Maze class的Maze() constructor,难道不用先定义
: 一个Maze 对象吗？
: 谢谢。
: #include
: #include
: #include
| k*******3
发帖数: 1909 | 3 Thanks！
For this book, actually my boss recommended it.
And I also check the amazon review, seems not bad.
http://www.amazon.com/Data-Structures-Algorithms-Adam-Drozdek-d
By your saying, I am actually confused whether this is a good book or not,
since I am not C++ expert.
Thanks for you answer anyway.
【在 p***o 的大作中提到】
:
: Somewhat yes.
: No, you are creating a temporary one by saying Maze().
: Well, it seems the whole piece of code is of bad taste. I don't think
: anyone will write C++ like that in production code. Get a better book
: from someone that knows how to write C++ programs.
| t****t
发帖数: 6806 | 4 The data structure part may be good or bad, I don't know.
But obviously, the c++ level of the author is mediocre, if not bad. And as a
code example, it added in too much noise to express the point, e.g.
included but actually used , redefined std::stack to
make pop return top(), defined Cell but actually should use std::pair<>, etc
., basically a total failure.
There are plenty of good books about data structures. Get a better one.
【在 k*******3 的大作中提到】
: Thanks！
: For this book, actually my boss recommended it.
: And I also check the amazon review, seems not bad.
: http://www.amazon.com/Data-Structures-Algorithms-Adam-Drozdek-d
: By your saying, I am actually confused whether this is a good book or not,
: since I am not C++ expert.
: Thanks for you answer anyway.
| k*******3
发帖数: 1909 | 5 Many Thanks!
a
etc
【在 t****t 的大作中提到】
: The data structure part may be good or bad, I don't know.
: But obviously, the c++ level of the author is mediocre, if not bad. And as a
: code example, it added in too much noise to express the point, e.g.
: included but actually used , redefined std::stack to
: make pop return top(), defined Cell but actually should use std::pair<>, etc
: ., basically a total failure.
: There are plenty of good books about data structures. Get a better one.
| k*******3
发帖数: 1909 | 6 能不能推荐本用C++写得算法和数据结构的好书？
谢谢！
a
etc
【在 t****t 的大作中提到】
: The data structure part may be good or bad, I don't know.
: But obviously, the c++ level of the author is mediocre, if not bad. And as a
: code example, it added in too much noise to express the point, e.g.
: included but actually used , redefined std::stack to
: make pop return top(), defined Cell but actually should use std::pair<>, etc
: ., basically a total failure.
: There are plenty of good books about data structures. Get a better one.
| t****t
发帖数: 6806 | 7 不能, 我这两个分开学的
【在 k*******3 的大作中提到】
: 能不能推荐本用C++写得算法和数据结构的好书？
: 谢谢！
:
: a
: etc
| k*******3
发帖数: 1909 | 8 haha, thanks!
【在 t****t 的大作中提到】
: 不能, 我这两个分开学的
|
|
