为什么我的C ++正则表达式不起作用？

Question

好的，所以我正在尝试学习c ++正则表达式，我遇到了一些问题。我查了一下代码，至少对我来说，这是合乎逻辑的。我还使用正则表达式测试器在线测试它，它成功地匹配了我的字符串。前两个（nameParser和anotherNameParser）不起作用，但最后一个（sampleParser）起作用。我真的不明白为什么它没有验证我的字符串。下面我包括了一个屏幕截图：

//http://rextester.com/tester
//compile with g++ -std=gnu++11 main.cpp -o main
#include <iostream>
#include <regex>
using namespace std;

/* * (nameParser)
 * Beginning at the front of the string, any set of character followed by at least one or more spaces 
 * followed by any set of characters with exactly one preceding dot, 
 * then followed by at least one or more spaces followed by any set of characters and end of string
 */

 //Need the extended or basic because any version less than 4.9 doesn't fully support c++11 regular expressions (28.13).
 //The error is because creating a regex by default uses ECMAScript syntax for the expression, which doesn't support brackets.
const regex nameParser("^[a-zA-Z]+\\s+[a-zA-Z]\\.{1}\\s+[a-zA-Z]+$",regex::extended);
const regex anotherNameParser("[a-zA-Z]+",regex::extended);
const regex sampleParser("(abc)");

int main() {
    //simple regex testing
    string name = "bob R. Santiago";
    if(regex_match(name, nameParser)) {
        cout << "name is valid!" << endl;
    } else cout << "Error in valdiating name!" << endl;

    string anotherName = "Bobo";
    if(regex_match(anotherName, anotherNameParser)) {
            cout << "name is valid!" << endl;
    } else cout << "Error in valdiating name!" << endl;

    string sample = "abc";
    if(regex_match(sample, sampleParser)) {
            cout << "name is valid!" << endl;
    } else cout << "Error in valdiating name!" << endl;

    return 0;
}

Answer 1

//Need the extended or basic because gnu gcc-4.6.1 doesn't fully support c++11 regular expressions (28.13).

尽管存在<regex>标题，但它在版本4.9之前并不支持所有 。

有时看起来可能会做你想要的，但它基本上没有。

升级到GCC 4.9。

Answer 2

在GCC 4.9之前未添加对<regex>的支持。请参阅release notes：

  

运行时库（libstdc ++）

     

  
• 改进了对C ++ 11的支持，包括：   
    
  • 支持<regex>;