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std::basic_regex<CharT,Traits>::mark_count

來自 cppreference.com
< cpp‎ | regex‎ | basic_regex
 
C++
 
文字處理庫
 
正則表示式庫
類
(C++11)
(C++11)
(C++11)
演算法
(C++11)
(C++11)
(C++11)
迭代器
(C++11)
(C++11)
異常
(C++11)
特性
(C++11)
常量
(C++11)
(C++11)
(C++11)
正則表示式語法
(C++11)
 
std::basic_regex
 
unsigned mark_count() const;
 (C++11 起)

返回正則表示式中被標記的子表示式（也稱為捕獲組）的數量。

目錄

[編輯] 引數

(無)

[編輯] 返回值

正則表示式中被標記的子表示式的數量。

[編輯] 異常

可能丟擲實現定義的異常。

[編輯] 示例

執行此程式碼
#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
}

輸出

r1 has 0 subexpressions
r2 has 1 subexpressions
r3 has 2 subexpressions
r4 has 2 subexpressions
r5 has 1 subexpressions
r6 has 0 subexpressions
取自 "https://cppreference.tw/mwiki/index.php?title=cpp/regex/basic_regex/mark_count&oldid=161002"