c++ - 为什么我的 Boost.Regex 搜索只报告一次匹配迭代？

Question

我试图找出一个字符串中有多少个正则表达式匹配项。我正在使用迭代器来迭代匹配项，并使用整数来记录有多少匹配项。

long int before = GetTickCount();
string text;

boost::regex re("^(\\d{5})\\s(\\d{8})\\s(.*)\\s(.*)\\s(.*)\\s(\\d{8})\\s(.{1})$");
char * buffer;
long length;
long count;
ifstream f;


f.open("c:\\temp\\test.txt", ios::in | ios::ate);
length = f.tellg();
f.seekg(0, ios::beg);

buffer = new char[length];

f.read(buffer, length);
f.close();

text = buffer;
boost::sregex_token_iterator itr(text.begin(), text.end(), re, 0);
boost::sregex_token_iterator end;

count = 0;
for(; itr != end; ++itr)
{
    count++;
}

long int after = GetTickCount();
cout << "Found " << count << " matches in " << (after-before) << " ms." << endl;

在我的示例中，count 始终返回 1，即使我将代码放入 for 循环中以显示匹配项(而且有很多)。这是为什么？我做错了什么？

编辑

测试输入:

12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N

输出(没有匹配项):

Found 1 matches in 16 ms.

如果我将 for 循环更改为:

count = 0;
for(; itr != end; ++itr)
{
    string match(itr->first, itr->second);
    cout << match << endl;
    count++;
}

我得到这个作为输出:

12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
12345 12345678 SOME NAME SOMETHING 88888888 N
Found 1 matches in 47 ms.

Answer 1

呵呵。你的问题是你的正则表达式。将您的 (.\*) 更改为 (.\*?)(假设支持)。您认为您看到的每一行都匹配，但实际上您看到的是整个文本，因为您的模式是贪婪的。

要查看说明的问题，请将循环中的调试输出更改为:

cout << "[" << match << "]" << endl;