#include <array>
#include <iostream>
using namespace std;
struct SimpleDebugger
{
SimpleDebugger(int val = 0) : x(val) {
cout << "created" << endl;
}
SimpleDebugger(const SimpleDebugger &that) : x(that.x) {
cout << "copied" << endl;
}
~SimpleDebugger() {
cout << "killed!" << endl;
}
int getX() const {
return x;
}
void setX(int val) {
x = val;
}
private:
int x;
};
array<SimpleDebugger, 3> getInts(int i)
{
array<SimpleDebugger, 3> a;
a[0].setX(i);
a[1].setX(i + 1);
a[2].setX(i + 2);
cout << "closing getInts" << endl;
return a;
}
SimpleDebugger (*getIntsArray(int i)) [3] {
typedef SimpleDebugger SimpleDebugger3ElemArray [3];
SimpleDebugger3ElemArray *sd = new SimpleDebugger3ElemArray[1];
(*sd)[0].setX(i);
(*sd)[1].setX(i + 1);
(*sd)[2].setX(i + 2);
cout << "closing getIntsArray" << endl;
return sd;
}
ostream& operator << (ostream& os, const SimpleDebugger &sd) {
return (cout << sd.getX());
}
int main() {
auto x = getInts(5);
cout << "std::array = " << x[0] << x[1] << x[2] << endl;
auto y = getIntsArray(8);
cout << "Raw array = " << (*y)[0] << (*y)[1] << (*y)[2] << endl;
delete [] y;
}
输出
created
created
created
closing getInts
std::array = 567
created
created
created
closing getIntsArray
Raw array = 8910
killed!
killed!
killed!
killed!
killed!
killed!
我尝试了上面的这个程序,看看使用std::array
原始数组有多方便,我知道避免使用旧式数组是一种很好的风格,更好的是使用std::vector
.
我想知道std::array
当函数getInts()
返回时,引擎盖下会发生什么。对于原始数组,我知道它是一个指针副本,清理它的责任落在被调用者身上。std::array
这不会发生,但它如何在内部存储数据以及复制如何发生?