#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
class Test
{
public:
Test()
{
m_a = 0;
m_b = 0;
cout << "0,0 構造" << endl;
}
Test(int a, int b)
{
m_a = a;
m_b = b;
cout << "a = " << m_a << ", b = " << m_b << "構造 " << endl;
}
void setA(int a)
{
m_a = a;
}
void setB(int b)
{
m_b = b;
}
void printT()
{
cout << "a = " << m_a << ", b = " << m_b << endl;
}
~Test()
{
cout << "a = " << m_a << ", b = " << m_b << "析構 " << endl;
}
private:
int m_a;
int m_b;
};
//C語言中
void test1()
{
int *p = (int*)malloc(sizeof(int));
*p = 10;
cout << *p << endl;
if (p != NULL) {
free(p);
//delete p; //delete 可以釋放malloc的開闢的內存
}
int *array_p = (int*)malloc(sizeof(int)* 10);
for (int i = 0; i < 10; i++) {
array_p[i] = i + 10;
}
for (int i = 0; i < 10; i++) {
cout << array_p[i] << endl;
}
if (array_p != NULL) {
free(array_p);
}
cout << " -------- " << endl;
Test *tp = (Test*)malloc(sizeof(Test)); //不會調用對象的構造函數
//p(10, 20);
tp->setA(10);
tp->setB(20); //malloc出來的對象指針,只能夠通過成員函數來進行初始化
tp->printT();
if (tp != NULL) {
free(tp); //不會調用對象的析構
}
}
//malloc 和free 在對於普通變量是可以混合使用的,但是malloc和free是函數,
//new 和delete 是操作符。不是一個函數。
//C++中的new delete
void test2()
{
//new 能夠完成所有malloc的需求
int *p = new int; //在堆上動態開闢4個字節
*p = 10;
cout << *p << endl;
if (p != NULL) {
//delete p; //delete 一個變量
free(p); //用new開闢的內存, free也能夠釋放。
}
cout << "-----" << endl;
int *array_p = new int[10];
for (int i = 0; i < 10; i++) {
array_p[i] = i + 10;
}
for (int i = 0; i < 10; i++) {
cout << array_p[i] << endl;
}
if (array_p != NULL) {
delete[] array_p; //delete 一個數組
}
cout << "-------" << endl;
//Test *tp = new Test(10, 20);//調用了有參數的構造函數 //new 在創建一個對象的時候,會調用對象的構造函數
Test *tp = new Test;//調用了無參構造函數
tp->printT();
if (tp != NULL) {
delete tp; //delete在釋放一個對象指針的時候,會調用對象析構函數
}
}
int main(void)
{
//test1();
test2();
return 0;
}