Question

使用链接列表实现Stack类。使用堆栈类验证XML文件。编写C ++程序以从命令行读取XML文件，并验证XML匹配不区分大小写的开始和结束标记。向所有缺少的相应开始或结束标记提供错误消息，并继续验证所有XML文件。

更正XML文档的示例。

<Students>
    <Student>
        <Name>Tanver</Name>
        <RollNo>312</RollNo>
    <student>
<students>

错误的XML文档示例，“head”和“html”结束标记丢失。 “名称”开始标记丢失。

<html>
    <head>
        <title>My first page</title>
        </name>
<body>
    My first page
</body>

Answer 1

我也在训练C ++，并认为这是一个很好的练习。以下是我提出的建议：

#include <iostream>
#include <vector>
#include <string>
#include <regex>

using namespace std;

template <typename T>
class Item {
    public:
        T data;
        Item *prev;
        Item(T& data, Item *prev) : data(data), prev(prev) {}
};

template <typename T>
class StackIterator {
    public:
        Item<T> *curr;

        StackIterator(Item<T> *curr) : curr(curr) {}

        T& operator*() { 
            return curr->data;
        }

        StackIterator<T>& operator++() {
            curr = curr->prev; 
            return *this; 
        }

        friend bool operator!=(const StackIterator<T>& l, const StackIterator<T>& r) {
            return l.curr != r.curr;
        }
};

template <typename T>
class Stack {
    typedef StackIterator<T> iterator;

    public:
        Item<T> *last=NULL;

        T& back(void) {
            return last->data;
        }

        void push_back(T d) {
            last = new Item<T>(d, last);
        }

        void pop_back(void) {
            Item<T> *curr = last;
            last = last->prev;
            delete curr;
        }

        ~Stack() {
            while (last) pop_back();
        }

        iterator begin() {
            return iterator(last);
        }

        iterator end() {
            return iterator(NULL);
        }
};

int main() {
    string xml[] = {"<Students>", "<Student>", "<Name>", "Tanver", "</Name>",
        "<RollNo>", "312", "</RollNo>", "</Student>", "</Students>"};

    //string xml[] = {"<html>", "<head>", "<title>", "My first page", "</title>",
    //    "</name>", "<body>", "My first page", "</body>"};

    regex opentag("^<(.*)>$");
    regex closetag("^</(.*)>$");
    smatch m;

    Stack<string> v;
    //vector<string> v;

    for (auto& it : xml) {
        if (regex_search(it, m, closetag)) {
            for (auto& x : m)
                if (x == v.back()) {
                    v.pop_back();
                    cout << "closing " << x << "\n";
                } else {
                    cout << "Tag " << x << " was not opened\n";
                }
        } else if (regex_search(it, m, opentag)) {
            for (auto &x : m) {
                cout << "opening " << x << "\n";
                v.push_back(x);
            }
        } else {
            cout << "data: " << it << "\n";
        }
    }

    for (auto& x : v) {
        cout << "Tag " << x << " was not closed\n";
    }
}

我没有打扰从命令行部分读取。当然，人们也可以跳过整个StackIterator的事情，但这就像用普通的C写整篇文章一样。

希望这有帮助！

使用链接列表实现堆栈类以验证xml文件

1 个答案: