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13. 정규표현식

1. 문자열 일치 확인

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    regex re(R"(\d+)");
    string str("1234");

    bool is_match = regex_match(str, re);

    cout << boolalpha;
    cout << "is_match = " << is_match << endl;

    return 0;
}

is_match = true


2. 문자열 숫자 검색

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    regex re(R"(\d+)");
    string str = "ab 123456 cd ef";
    smatch match_info;

    regex_search(str, match_info, re);

    cout << boolalpha;
    cout << "number: " << match_info.str() << endl;

    return 0;
}

number: 123456


3. 문자열 일부 변경

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    regex re1(R"(l|i|k|e)");
    regex re2(R"(\D)");
    regex re3(R"(\s)");
    string str = "i like coding";

    string result1 = regex_replace(str, re1, "[$&]");
    string result2 = regex_replace(str, re1, "*");
    string result3 = regex_replace(str, re2, "_$&_");
    string result4 = regex_replace(str, re3, "(space)");

    cout << "result1: " << result1 << endl;
    cout << "result2: " << result2 << endl;
    cout << "result3: " << result3 << endl;
    cout << "result4: " << result4 << endl;

    return 0;
}

result1: [i] [l][i][k][e] cod[i]ng
result2: * **** cod*ng
result3: _i__ __l__i__k__e__ __c__o__d__i__n__g_
result4: i(space)like(space)coding


4. 첫 번째 결과 변경

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    regex re(R"(\S)");
    string str = "i like coding";

    string result = regex_replace(str, re, "[$&]",
                                  regex_constants::format_first_only);

    cout << "result: " << result << endl;

    return 0;
}

result: [i] like coding


5. 모든 숫자 검색

#include <iostream>
#include <regex>
#include <string>
#include <vector>
using namespace std;

int main() {
    regex re(R"(\d+)");
    const string str = "12 34ab 56 cd78__ !9 10 ==11";
    vector<string> result;
    smatch match_info;

    auto start = str.begin();
    auto end = str.end();

    while (regex_search(start, end, match_info, re)) {
        result.push_back(match_info.str());
        start = match_info[0].second;
    }

    for (auto i : result)
        cout << i << ' ';
    cout << endl;

    return 0;
}

12 34 56 78 9 10 11


6. 특정 글자 검색 1

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    string str =
        "Wang Geon, a descendant of Go-gu-ryeo nobility, deemed the nation as the successor of Go-guryeo ";
    smatch match_info;
    regex re(" Go-([^ ]*)");

    while (regex_search(str, match_info, re)) {
        cout << match_info.str() << ' ' << endl;
        str = match_info.suffix().str();
    }

    return 0;
}

 Go-gu-ryeo
 Go-guryeo


7. 특정 글자 검색 2

#include <iostream>
#include <regex>
#include <string>
#include <vector>
using namespace std;

int main() {
    vector<string> Korea = {
        "Republic of Korea",
        "republic of Korea",
        "Republic of korea",
        "republic of korea",
        "South Korea",
        "south Korea",
        "South korea",
        "south korea",
    };
    regex re("([Rr]epublic)\\s.*");
    smatch match_info;

    for (auto i : Korea) {
        if (regex_match(i, match_info, re))
            cout << match_info[0] << endl;
    }

    return 0;
}

Republic of Korea
republic of Korea
Republic of korea
republic of korea


8. 특정 글자 검색 3

#include <iostream>
#include <regex>
#include <string>
#include <vector>
using namespace std;

int main() {
    vector<string> Korea = {
        "Republic of Korea",
        "republic of Korea, since 1945",
        "Republic of korea, since 1945",
        "republic of korea",
        "South Korea, since 1945",
        "south Korea",
        "SOUTH KOREA, since 1945",
        "south korea",
    };
    regex re("(SOUTH|south).*(1945)");
    smatch match_info;

    for (auto i : Korea) {
        if (regex_match(i, match_info, re))
            cout << match_info[0] << endl;
    }

    return 0;
}

SOUTH KOREA, since 1945


9. 모든 단어 검색

#include <iostream>
#include <regex>
#include <string>
using namespace std;

int main() {
    string str =
        "Jolbon Buyeo was the predecessor to Goguryeo, and in 538, Baekje renamed itself Nambuyeo (South Buyeo)";
    regex re("([A-Za-z]+)");

    auto start = sregex_iterator(str.begin(), str.end(), re);
    auto end = sregex_iterator();

    cout << "== 단어 개수: " << distance(start, end) << " ==" << endl;
    for (sregex_iterator i = start; i != end; ++i)
        cout << i->position() << ", " << i->str() << endl;

    return 0;
}

== 단어 개수: 15 ==
0, Jolbon
7, Buyeo
13, was
17, the
21, predecessor
33, to
36, Goguryeo
46, and
50, in
58, Baekje
65, renamed
73, itself
80, Nambuyeo
90, South
96, Buyeo