為了測試c++中對new操作符的運算規則是否呼叫預設物件的建構函式進行初始化，故寫出如下的測試demo:

#include <iostream> using namespace std; //using std::cout 或者using std::endl template <class eleType> void print_value(eleType *a, int size) { if(!a || size <=0) { cout << "(0) []" << endl; return; } cout << "(" << size << ") ["; eleType *start = a; eleType *end = a + (size-1); while(start != end) { cout << *start << " "; ++start; } cout << "]" << endl; } class item { public: item(){cout << "item init" << endl;} }; int main() { int *p; //其實會初始化成0 p = new int; cout << "value of new int:" << *p << endl; //cout << p; //會初始化成0 p = new int(); cout << "value of new int():" << *p << endl; //會初始化成0 p = new int(1024); cout << "value of new int(1024):" << *p << endl; //i此時是一個隨機數 int i; cout << "value of int i:" << i << endl; //此時會初始化為0 int j = int(); cout << "value of int():" << j << endl; //測試陣列的情況,對陣列的每個值均初始化為0 int *pia = new int[10]; print_value(pia, 10); //初始化空字串 string *pstr = new string; cout << "value of new string:" << *pstr << endl; //均會呼叫對應的預設建構函式，所以所有的字串均為空字串 string *psa = new string[10]; print_value(psa, 10); //均會呼叫對應的預設建構函式，所以所有的字元均為空 char *pch = new char[10]; print_value(pch, 10); //均衡呼叫每個item的預設建構函式 item *pItem = new item[10]; }

執行結果如下：

 ./testNewDelete

value of new int:0
value of new int():0
value of new int(1024):1024
value of int i:0
value of int():0
(10) [0 0 0 0 0 0 0 0 0 ]
value of new string:
(10) [         ]
(10) [         ]
item init
item init
item init
item init
item init
item init
item init
item init
item init
item init