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 <iostream> // Required for cin, cout, cerr
#include <fstream> // Required for ifstream, ofstream
#include <string> // Required for string
#include <cstdlib> // Required for exit
using 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 :
( *.*, such as : demo.html )
" ;
cout << "Make sure the file is under current project file !
" ;
// My English is poor ~~
cin >> infile;
cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
" ;
// 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<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
" ;
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<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
" ;
cout << "Success transformed !
" ;
cout << "Look for " << outfile << " in current file.
" ;
cout<< "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
" ;
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：
<html> <head> <title>我的第一个 HTML 页面</title> </head> <body> <p>body 元素的内容会显示在浏览器中。</p> <p>title 元素的内容会显示在浏览器的标题栏中。</p> </body> </html>