实验测试1《C++ Primer》第五版——第十三章 拷贝控制

String.h

#ifndef STRING_H#define STRING_H#include <cstring>#include <algorithm>#include <cstddef>#include <iostream>#include <iostream>#include <memory>using namespace std;class String {    friend String operator+(const String&, const String&);    friend ostream &operator<<(std::ostream&, const String&);public:    String() : sz(0), p(nullptr) {    }    String(const char *cp) : sz(std::strlen(cp)), p(a.allocate(sz)) {        cout << "String(const char *cp)" << endl;        uninitialized_copy(cp, cp + sz, p);    }    String(const String &s) : sz(s.sz), p(a.allocate(s.sz)) {        cout << "String(const String &s)" << endl;        uninitialized_copy(s.p, s.p + sz, p);    }    String(String &&s) : sz(s.sz), p(s.p) {        cout << "String(String &&s)" << endl;        s.p = nullptr;        s.sz = 0;    }    ~String() {        cout << "~String()" << endl;        if (p) a.deallocate(p, sz);    }    String &operator=(const String &);    String &operator=(String&&);    String &operator=(const char*);    const char *begin() {        return p;    }    const char *begin() const {        return p;    }    const char *end() {        return p + sz;    }    const char *end() const {        return p + sz;    }    size_t size() const {        return sz;    }    void swap(String &s) {        char *tmp = p;        p = s.p;        s.p = tmp;        size_t cnt = sz;        sz = s.sz;        s.sz = cnt;    }private:    size_t sz;    char *p;    static allocator<char> a;};#endif /* STRING_H */

String.cpp

#include "String.h"std::allocator<char> String::a;String &String::operator=(const String &s) {    cout << "operator=(const String &s)" << endl;    char *newp = a.allocate(s.sz);    uninitialized_copy(s.p, s.p + s.sz, newp);    if (p)        a.deallocate(p, sz);    p = newp;    sz = s.sz;    return *this;}String &String::operator=(String &&s) {    cout << "operator=(String &&s)" << endl;    if (p)        a.deallocate(p, sz);    p = s.p;    sz = s.sz;    s.p = nullptr;    s.sz = 0;    return *this;}String &String::operator=(const char *cp) {    cout << "operator=(const char *cp)" << endl;    if (p) a.deallocate(p, sz);    p = a.allocate(sz = strlen(cp));    uninitialized_copy(cp, cp + sz, p);    return *this;}ostream &operator<<(ostream &os, const String &s) {    const char *p = s.begin();    while (p != s.end())        os << *p++ ;    return os;}String operator+(const String &lhs, const String &rhs) {    String ret;    ret.sz = rhs.size() + lhs.size();    ret.p = String::a.allocate(ret.sz);    uninitialized_copy(lhs.begin(), lhs.end(), ret.p);    uninitialized_copy(rhs.begin(), rhs.end(), ret.p + lhs.sz);    return ret;}

main.cc

#include "String.h"using namespace std;int main(int argc, char* argv[]) {    allocator<String> alloc;    auto const p = alloc.allocate(4);    String s1("String1");    String s2 = s1;    String s3 = move(s1);    String s4(move(s2));    cout << "s1:" << s1 << endl;    cout << "s2:" << s2 << endl;    cout << "s3:" << s3 << endl;    cout << "s4:" << s4 << endl;    return 0;}

输出结果

String(const char *cp)String(const String &s)String(String &&s)String(String &&s)s1:s2:s3:String1s4:String1~String()~String()~String()~String()