C++ match_results size()用法及代码示例

match_results size()是C++中的内置函数，它返回match_result对象中的匹配数和sub-matches。

用法:

smatch_name.size()

Note: smatch_name is an object of match_results class.

参数：该函数不接受任何参数。

返回值：它返回match_result对象中的匹配数。

注意：第一个元素始终包含整个正则表达式匹配项，而其他元素则包含特定的捕获组

以下示例程序旨在说明上述函数。

示例1:

// CPP program to illustrate 
// match_results size() in C++ 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    string s("Geeksforgeeks"); 
    regex re("(Geeks)(.*)"); 
  
    smatch match; 
  
    // Function call to find match 
    regex_match(s, match, re); 
  
    cout << "match size is " << match.size() << endl; 
  
    return 0; 
}

输出：

match size is 3

示例2:

// CPP program to illustrate 
// match_results size() in C++ 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    string s("Geeksforgeeks"); 
    regex re("(Geeks)(.*)"); 
  
    smatch match; 
  
    // Function call to find matches 
    regex_match(s, match, re); 
  
    cout << "match size is " << match.size() << endl; 
  
    for (int i = 0; i < match.size(); i++) { 
        cout << "match " << i << " has a length of "
             << match.length(i) << endl; 
    } 
    return 0; 
}

输出：

match size is 3
match 0 has a length of 13
match 1 has a length of 5
match 2 has a length of 8

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注：本文由纯净天空筛选整理自Harsha_Mogali大神的英文原创作品 match_results size() in C++ STL。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。