定位new

placement_new.cpp

/*
 * 定位new
 */
#include <iostream>
using namespace std;

char g_addr[100];

int main() {
    // 把内存分配到全局区
    //int* p = new(g_addr)int;
    int* p = new(g_addr)int(3); //赋初值
    *p = 2;
    cout << static_cast<void*>(g_addr) << " " << static_cast<void*>(p) << "  " << *p << endl;

    // 把内存分配到栈区
    char l_addr[100];
    p = new(l_addr)int[2];
    p[0] = 1;
    p[1] = 2;
    cout << static_cast<void*>(l_addr) << " " << static_cast<void*>(p) << " " << p[0] << " " << p[1] << endl;

    // 把内存分配到堆区
    char *h_addr = new char[100];
    p = new(h_addr)int[2]{4, 5};
    cout << static_cast<void*>(h_addr) << " " << static_cast<void*>(p) << " " << p[0] << " " << p[1] << endl;
    delete[] h_addr;

    return 0;
}