编写一个C++程序来读取文件，过滤掉所有的标记，将过滤掉标记后的内容输出到一个新文件中。

1. 从文件中读取一个字符

2. 确定字符是否是HTML标记的一部分

3. 打印出所有不是HTML标记的字符

/* -------------------------------------------- * This program reads a html file, and writes * the text without the tags to a new file. * --------------------------------------------*/#include 
    
      // Required for cin, cout, cerr#include 
     
        // Required for ifstream, ofstream#include 
      
          // Required for string#include 
       
          // Required for exitusing namespace std;int main(){    // Declare objects    char ch;    bool text_state(true);    string infile, outfile;    ifstream html;    ofstream htmltext;    // Prompt user for name of input file    cout << "Enter the name of the input file : \n( *.*, such as : demo.html ) \n" ;    cout << "Make sure the file is under current project file ! \n" ;    // My English is poor ~~    cin >> infile;    cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" ;    // Prompt user for name of output file    cout << "Enter the name of the output file :  " ;    cin >> outfile;    // Open files    html.open(infile.c_str());    if(html.fail())    {        cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" ;        cerr << "Error opening input file" << endl ;        exit(1);    }    htmltext.open(outfile.c_str());    // Read first character from html file    html.get(ch);    while(!html.eof())    {        // Check state        if(text_state)        {            if(ch == '<')                // Beginning of a tag                text_state = false;                // Change states            else                htmltext << ch;                // Still text, write to the file        }        else        {            // Command state, no output required            if(ch == '>')            // End of tag                text_state = true;            // Change states        }        // Read next character from html file        html.get(ch);    }    html.close();    htmltext.close();    cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" ;    cout << "Success transformed ! \n" ;    cout << "Look for " << outfile << " in current file.\n" ;    cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" ;    return 0;}
       
      
     
    

之后就可以拿个HTML文件试试了，不过这个程序只是把所有标记过滤掉，还有待完善。如果非标记字符有很多无关内容，效果就差强人意。建议用典型的HTML文件测试，如：

body 元素的内容会显示在浏览器中。
title 元素的内容会显示在浏览器的标题栏中。