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;

}
}
}