将C/C++代码中的注释删除

题目：

将C/C++代码中的注释通过程序删除。

分析：

C/C++中的代码注释，包括如下形式：//, /* */。

当然，在""和''中的//, /* */是无效的，不应删除。

因此，可以考虑针对/, *, ", '加标志flag1, flag2, flag3, flag4：

1）遇到/时，读取下一个字符，如果是/时，则将当前行删除；如果是*,记录当前位置，找到*/，然后删除之间的字符；

2）遇到"或者'时，flag3, flag4置为true，在"或'中的注释忽略掉。

代码如下：

//============================================================================
// Name        : DeleteComments.cpp
// Author      :
// Version     :
// Copyright   : All rights reserved
// Description : 去掉C/C++程序中的注释
//		 1. //...
//		 2. /*... */
//		 3. 特殊情况:
//		   (1) "//"  "/*" 不算注释
//		   (2) ''中的//和/*
//		   (3) 二者互相嵌套
//============================================================================

#include <iostream>
#include <fstream>
using namespace std;
void deleteComments(char *, int);

int main() {
	string filename;
	cout << "Please enter name for a cpp file:" << endl;
	cin >> filename;
	ifstream fin;
	try {
		fin.open(filename.c_str());
	} catch(std::exception &e)
	{
		cout << e.what() << endl;
	}

	if (fin.is_open())
	{
		cout << "Open " << filename << " successfully!" << endl;
	}
	char buf[102400];
	int n = fin.readsome(buf, sizeof(buf));//read(buf, sizeof(buf));
	if (n == -1)
	{
		fin.close();
	}
	deleteComments(buf, n);

	cout << "After Dealing: " << endl << buf <<endl;
	return 0;
}

void deleteComments(char* buf, int n)
{
	char *p, *end, c;

	p = buf;
	end = buf + n;

	char *pos1 = NULL, *pos2 = NULL;
	bool flag1 = false, flag2 = false;// "   and   '
	int flag3 = 0, flag4 = 0, flag5 = 0;// for /*...     //...      */

	while( p < end)
	{
		c = *p;
		cout << "new char: " << c <<endl;
		switch(c)
		{
			case '"':
			{
				if (flag3 == 0)
					flag1 = (flag1 == true)?false:true;
				p ++;
			} break;
			case '\'':
			{
				if (flag3 == 0)
					flag2 = (flag2 == true)?false:true;
				p ++;
			} break;
			case '/':
			{
				p ++;
				if (*p == '/' && (flag3 == 0))    // ..... //....
				{
					p ++;
					cout << "in // " << endl;
					cout << " falg3: " << flag3 << "  flag5: " << flag5 << "  flag1: " << flag1 << "  flag2: " << flag2 << endl;
					if (!flag1 && !flag2 && (flag5 == 0) && (flag4 == 0) && (flag3 == 0))
					{
						//flag4 ++;
						// deal with //...:delete char until '\n'
						cout << "deal with // ..." << endl;

						*(p-1) = ' ';
						*(p-2) = ' ';
						while (*p != '\n')
						{
							cout << "dealing : " << *p << "   ";
							*p = ' ';
							p ++;
						}
					}

				}
				else if ( *p == '*' && !flag1 && !flag2 && (flag3 == 0))    // ....  /*.....
				{
					p ++;
					flag3 ++;
					cout << " falg3: " << flag3 << "  flag5: " << flag5 << "  flag1: " << flag1 << "  flag2: " << flag2 << endl;
					if (!flag1 && !flag2 && (flag4 == 0) && (flag3 == 1))
					{
						pos1 = p;// delete from pos1
					}
				}
			}break;
			case '*':
			{
				p ++;
				if (*p == '/' && !flag1 && !flag2)  // .... */...
				{
					flag5 ++;
					cout << " falg3: " << flag3 << "  flag5: " << flag5 << "  flag1: " << flag1 << "  flag2: " << flag2 << endl;
					if(!flag1 && !flag2 && (flag3 != 0) && (flag5 != 0))
					{
						flag3 = 0;
						flag5 --;
						pos2 = p - 2;
						cout << "deal with  \/* .. *\/" << endl;
						// deal wtih /*... */... : delete from pos1 to pos2
						char *pos = pos1;
						*(pos - 1) = ' ';
						*(pos - 2) = ' ';
						*(pos2 + 1) = ' ';
						*(pos2 + 2) = ' ';

						do {
							cout << "dealing: " <<  *pos << endl;
							*pos = ' ';
							pos ++;
						} while(pos != pos2 + 1);
					}
				}
			} break;
			default:
				p ++;
				break;

		}
	}
}