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6_4_3_copy-test.cpp
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129 lines (110 loc) · 3.58 KB
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// file: 6copy-test.cpp
#include <iostream> // for cout
#include <algorithm> // for copy()
#include <vector>
#include <deque>
#include <list>
// #include "string.h"
using namespace std;
class C {
public:
C() : _data(3) { } //显式定义了构造函数，所以是non-trivial ctor
// there is a trivial assignment operator
//没有显式定义ctor/dtor/copy/assignemt所以都是trivial
private:
int _data;
};
class String {
public:
String() : _data("") {} // 需要定义无参构造函数
String(string s) : _data(s) { } //显式定义了构造函数，所以是non-trivial ctor
String(const char* c) : _data(c) { }
// 有显式定义assignemt所以是non-trivial
String& operator=(const String& S) {
_data = S._data;
return *this;
}
String& operator=(const char* c) {
_data = c;
return *this;
}
private:
string _data;
};
int main() {
const char ccs[5] = {'a', 'b', 'c', 'd', 'e'};
char ccd[5];
// 调用copy(const char*)
copy(ccs, ccs + 5, ccd);
const wchar_t cwcs[5] = {'a', 'b', 'c', 'd', 'e'};
wchar_t cwcd[5];
copy(cwcs, cwcs + 5, cwcd);
// 调用copy(const wchar_t*)
int ia[5] = {0, 1, 2, 3, 4};
copy(ia, ia + 5, ia);
// 调用
// copy()
// __copy_dispatch(T*, T*)
// __copy_t(__true_type)
// list迭代器为InputIterator
list<int> ilists(ia, ia + 5);
list<int> ilistd(5);
copy(ilists.begin(), ilists.end(), ilistd.begin());
// 调用
// copy()
// __copy_dispatch()
// __copy(input_iterator)
// vector迭代器为原生指针
vector<int> ivecs(ia, ia + 5); // vector的ctor会调用copy
vector<int> ivecd(5);
copy(ivecs.begin(), ivecs.end(), ivecd.begin());
// copy()
// __copy_dispatch(T*, T*)
// __copy_t(__true_type) 为什么不是__copy(random_access_iterator)
// 因为是原生指针
// class C具备trivial operator=
C c[5];
vector<C> Cvs(c, c + 5);
vector<C> Cvd(5);
copy(Cvs.begin(), Cvs.end(), Cvd.begin());
// copy()
// __copy_dispatch(T*, T*)
// __copy_t(_false_type) 为什么不是__true_type
// __copy_d() 因为编译器不一定能验证自定义类的类型特性
// 被视为拥有non-trivial ctor/dtor/operator=
// 需要自己手动为class C做特化版本
// deque迭代器为random access iterator
deque<C> Cds(c, c + 5);
deque<C> Cdd(5);
copy(Cds.begin(), Cds.end(), Cdd.begin());
// copy()
// __copy_dispatch()
// __copy(random_access_iterator)
// __copy_d()
// string拥有non-trivial opeartor=
vector<String> strvs(5);
vector<String> strvd(5);
strvs[0] = "jjhou"; // 需要重载operator(const char*)
strvs[1] = "grace";
strvs[2] = "david";
strvs[3] = "jason";
strvs[4] = "jerry";
copy(strvs.begin(), strvs.end(), strvd.begin());
// copy()
// __copy_dispatch(T*, T*) 为什么不是__copy(random_access_iterator)
// __copy_t(_false_type)
// __copy_d()
// deque迭代器为random access iterator
deque<String> strds(5);
deque<String> strdd(5);
strds.push_back("jjhou"); // 需要定义String(const char*)
strds.push_back("grace");
strds.push_back("david");
strds.push_back("jason");
strds.push_back("jerry");
copy(strds.begin(), strds.end(), strdd.begin());
// copy()
// __copy_dispatch()
// __copy(random_access_iterator)
// __copy_d()
}