std::basic_regex<CharT,Traits>::mark_count
来自 cppreference.com
< cpp | regex | basic regex
| unsigned mark_count() const; |
(自 C++11 起) | |
返回正则表达式中标记的子表达式（也称为捕获组）的数量。
内容 |
[编辑] 参数
(无)
[编辑] 返回值
正则表达式中标记的子表达式的数量。
[编辑] 异常
可能会抛出实现定义的异常。
[编辑] 示例
运行此代码
#include <iostream> #include <regex> int main() { std::regex r1{"abcde"}; std::cout << "r1 has " << r1.mark_count() << " subexpressions" << '\n'; // Expected: 0 std::regex r2{"ab(c)de"}; std::cout << "r2 has " << r2.mark_count() << " subexpressions" << '\n'; // Expected: 1 std::regex r3{"a(bc)d(e)"}; std::cout << "r3 has " << r3.mark_count() << " subexpressions" << '\n'; // Expected: 2 // Nested sub-expressions std::regex r4{"abc(de(fg))"}; std::cout << "r4 has " << r4.mark_count() << " subexpressions" << '\n'; // Expected: 2 // Escaped parentheses std::regex r5{"a(bc\\(\\)de)"}; std::cout << "r5 has " << r5.mark_count() << " subexpressions" << '\n'; // Expected: 1 // Using nosubs flag std::regex r6{"ab(c)de", std::regex_constants::nosubs}; std::cout << "r6 has " << r6.mark_count() << " subexpressions" << '\n'; // Expected: 0 }
输出
r1 has 0 subexpressions r2 has 1 subexpressions r3 has 2 subexpressions r4 has 2 subexpressions r5 has 1 subexpressions r6 has 0 subexpressions
