为什么我的C ++正则表达式不起作用？

好的，所以我正在尝试学习c ++正则表达式，但遇到了一些麻烦。我仔细阅读了代码，至少对我而言，这是合乎逻辑的。我还使用正则表达式测试仪在线测试了它，并成功匹配了我的字符串。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不能验证我的字符串。下面，我包括一个屏幕截图：

//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;
}