C++ String 구현 해 보기

String의 작동원리를 대강이나마 알 수 있기 때문에 만들어 보았습니다.

물논 예전에 만들었습니다.

#pragma warning(disable : 4996)
#include <iostream>
#include <cstring>
using namespace std;
 
class Mystring
{
    char *str; //문자메모리공간 할당
    int len; //문자열 길이저장변수
    
public:
    Mystring(const char *p) //생성자함수호출
    {
        // 문자열 길이 구하기
        len = strlen(p)+1; //문자열 마지막에 NULL!
        // 메모리 할당
        str = new char[len];
         //문자열 복사
        strcpy(str, p);
    }
 
    Mystring(const int len)
    {
        this->len = len;
        str = new char[len];
    }
 
    Mystring(const int data, const char dol) //생성자함수 호출
    {
        str = new char[data+1];
        for (int i = 0; i < data; i++) {
            str[i] = dol;
        }
        str[data] = NULL;
    }
    Mystring(const Mystring & aa) { //복사 생성자함수 호출
        len = strlen(aa.str) + 1;
        str = new char[len];
        strcpy(str, aa.str);
        
    }
 
    Mystring& operator += (const char *p) //+= 연산자함수 호출
    {
        char *temp;
        len = strlen(this->str)+strlen(p)+1;
        temp = new char[len];
        strcpy(temp, this->str);
        delete[] str;
        this->str = new char[len];
        strcpy(this->str, temp);
        delete[] (temp);
        strcat(this->str, p);
        return *this;
    }
 
    Mystring & operator = (const char *p) //대입연산자함수 호출
    {
        len = strlen(p)+1;
        str = new char[len];
        //this->str = p;
        strcpy(str, p);
        return *this;
    }
 
    char& operator [] (int dol) //첨자
    {
 
        return this->str[dol];
    }
 
 
 
    Mystring() {
        //str = new char[1000];
        //len = 1000;
        len = 0;
        str = NULL;
    }
 
    Mystring operator + (Mystring& aa)    // four = two + three;    four.operator=(two.operator+(three));
    {    
        /*Mystring  res;
        char *temp;
        int len2;
        len2 = strlen(str) + strlen(aa.str) + 1;
        temp = new char[len2];
        
        strcpy(temp, str);
        strcat(temp, aa.str);
        res.str = temp;
        return res;*/
        Mystring *res;
        res = new Mystring(strlen(str) + strlen(aa.str) + 1);
        strcpy(res->str, str);
        strcat(res->str, aa.str);
        return *res;
        
    }
 
    Mystring& operator = (const Mystring &cc) {
 
        len = strlen(cc.str)+1;
        str = new char[len];
        //*str = *cc.str;
        strcpy(this->str, cc.str);
        return *this;
    }
 
 
    Mystring(const char *ab, int data) {
 
        str = new char[data+1];
        for (int i = 0; i < data; i++) {
            str[i] = ab[i];
        }
        str[data] = NULL;
    }
 
    Mystring(const char *a , const char *b) {
        len = b-a+1;
        str = new char[len];
        for (int i = 0; i < len; i++) {
            str[i] = a[i];
            
        }
        str[len-1] = NULL;
        
    }
 
    ~Mystring() {
        delete[] str;
    }
 
 
    friend ostream& operator<<(ostream &out, const Mystring &obj);
    friend istream& operator >>(istream &in, Mystring &obj);
};
 
 
ostream& operator<<(ostream &out, const Mystring &obj)
{
    
    out << obj.str;
    return out;
}
 
istream& operator >>(istream &in, Mystring &obj)
{
    /*obj.len = strlen(obj.str);

    char *p = new char[obj.len + 1];
    in >> p;
    
    if(obj.str != NULL) delete obj.str;
    obj.str = p;
    */
 
    char *buf = new char[1000];
    in >> buf;
    obj.len = strlen(buf) + 1;
    obj.str = new char[obj.len];
 
    strcpy(obj.str, buf);
 
    delete []buf;
    return in;
}
 
 
 
 
 
 
void main()
{
    Mystring one("lottery winner!");//생성자함수호출
    cout << one << endl;  //출력연산자함수호출
 
    Mystring two(20, '$');//생성자함수호출
    cout << two << endl;//출력연산자함수호출
 
    Mystring three(one); // 복사생성자호출
    cout << three << endl; //출력연산자함수호출
 
    one += "oops"; // +=연산자함수호출 ( strcat함수 )
    cout << one << endl;//문자열결합 
 
    two = "sorry!that was";//대입연산자함수 호출 
    cout << two << endl;
 
    three[0] = 'p';//[]첨자연산자함수 호출 
    cout << three << endl;
 
 
    Mystring four;
    four = two + three;// four.operation=(two.operation +( three ))
    cout << four << endl;
 
    char alls[] = "all's well that ends well";
    Mystring five(alls, 20); //생성자호출
    cout << five << "!\n";
 
 
    Mystring six(alls + 6, alls + 10);  //생성자
    cout << six << ",";
 
 
    Mystring seven(&five[6], &five[10]);  //생성자
    cout << seven << "...\n";
 
    Mystring eight;
    cout << "문자열 입력하세요 :";
    cin >> eight;  // >>연산자호출
    cout << " 입력한 문자열은 \"" << eight << "\" 입니다 " << endl;
 
}