Question

我的教授给了我一些关于boggle游戏回溯的c ++代码。但它不会为我编译。我收到此错误，使用未声明的标识符＆＃39; top＆＃39 ;;你是说＆＃39; pop＆＃39;？如果需要的话，还有其余的代码。谢谢！

// Maze01.cpp : Defines the entry point for the console application.

#include <cstdlib>
#include <iostream>
#include <stack>
using namespace std;
template<class T>
class Stack : public stack<T> {
public:
    T pop() {
        T tmp = top(); //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
        stack<T>::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<Cell> 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<char*> 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(int argc, char* argv[])
{

    Maze().exitMaze();
    return 0;
}

Answer 1

以这种方式修复：

    T tmp = this->top(); //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

gcc5.3解释了原因：

/tmp/gcc-explorer-compiler116315-75-7jbdnd/example.cpp: 
    In member function 'T Stack<T>::pop()':
13 : error: there are no arguments to 'top' that depend on a template parameter, 
    so a declaration of 'top' must be available [-fpermissive]
T tmp = top(); //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
^
13 : note: (if you use '-fpermissive', G++ will accept your code, 
    but allowing the use of an undeclared name is deprecated)
Compilation failed

使用未声明的标识符＆＃39; top＆＃39;;你是说＆＃39; pop＆＃39;？

1 个答案: