0、核心要素
// 構(gòu)造、析構(gòu)函數(shù)私有化（一個進程只允許一個對象存在）
// 對象私有化、靜態(tài)化（因為接口靜態(tài)函數(shù)）
// 對象調(diào)用接口靜態(tài)化（因為靜態(tài)函數(shù)脫離了類對象，可以直接調(diào)用）
一、懶漢
唯一的對象在使用時才進行初始化。存在多線程問題。文章來源：http://www.zghlxwxcb.cn/news/detail-653600.html
#include <iostream>
using namespace std;
class singleMode {
public:
static singleMode* getInstance() {
if (obj==nullptr) {
obj = new singleMode();
}
return obj;
}
void printMsg() {
cout << "print success." << endl;
}
private:
static singleMode* obj;
singleMode() {
cout << "instance create." << endl;
}
~singleMode() {
cout << "instance release." << endl;
}
};
singleMode* singleMode::obj = nullptr;
// singleMode* singleMode::obj = new singleMode();
int main()
{
{
singleMode::getInstance()->printMsg();
}
return 0;
}
二、餓漢
唯一的對象在定義時就完成初始化。文章來源地址http://www.zghlxwxcb.cn/news/detail-653600.html
#include <iostream>
using namespace std;
class singleMode {
public:
static singleMode* getInstance() {
/* if (obj==nullptr) {
obj = new singleMode();
}
*/
return obj;
}
void printMsg() {
cout << "print success." << endl;
}
private:
static singleMode* obj;
singleMode() {
cout << "instance create." << endl;
}
~singleMode() {
cout << "instance release." << endl;
}
};
// singleMode* singleMode::obj = nullptr;
singleMode* singleMode::obj = new singleMode();
int main()
{
{
singleMode::getInstance()->printMsg();
}
return 0;
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