범위 기반 for문 및 문자열 분할

1. 범위 기반 for문

for (string input : answer)  // 아래의 코드와 같은 구문
    cout << input << ' ';
 
for (vector<string>::iterator input = answer.begin(); input != answer.end(); ++input)
    cout << *input << ' ';
 

for (vector<string> input : relation) {
    for (string in : input)
        cout << in << ' ';
    cout << endl;
}
 
for (vector<vector<string>>::iterator input = relation.begin(); input != relation.end(); ++input) {
    for (vector<string>::iterator in = (*input).begin(); in != (*input).end(); ++in)
        cout << *in << ' ';
    cout << endl;
}

2. 문자열 분할

for (string input : record)
{
    stringstream ss(input);
    ss >> command;
    ss >> uid;
    if (command == "Enter" || command == "Change")
    {
        ss >> ID;
        m[uid] = ID;
    }
}

3. 문제를 통한 예시(카카오 코딩 테스트 1번 오픈채팅방)

#include <string>
#include <vector>
#include <sstream>
#include <iostream>
#include <map>
using namespace std;
 
 
vector<string> solution(vector<string> record) {
    vector<string> answer;
    string command;
    string ID;
    string uid;
    map<string, string> m;
 
 
    for (auto input : record)
    {
        stringstream ss(input);
        ss >> command;
        ss >> uid;
        if (command == "Enter" || command == "Change")
        {
            ss >> ID;
            m[uid] = ID;
        }
    }
 
    for (string input : record)
    {
        stringstream ss(input);
        ss >> command;
        ss >> uid;
        if (command == "Enter")
        {
            ID = (m.find(uid)->second);
 
            string temp = ID + "님이 들어왔습니다.";
            answer.push_back(temp);
 
        }
        else if (command == "Leave")
        {
            ID = (m.find(uid)->second);
            string temp = ID + "님이 나갔습니다.";
            answer.push_back(temp);
        }
    }
    return answer;
}
 
int main()
{
    vector<string> answer;
    answer = { "Enter uid1234 Muzi", "Enter uid4567 Prodo", 
        "Leave uid1234", "Enter uid1234 Prodo", "Change uid4567 Ryan" };
    for (vector<string>::iterator input = answer.begin(); input != answer.end(); ++input)
    {
        cout << *input << ' ';
    }
    return 0;
}