走進C++程序世界-----operator new delete 重載
阿新 • • 發佈：2018-04-01
net .net mail RM 釋放空間 pos mar alloc eas
?在C++ 的世界裏，new 和delete 是keyword。而在C的世界裏相相應的malloc和free是函數，關鍵C++的new和delete分析，詳見前面的章節。這裏就不在過多的介紹了。鏈接。
以下來研究下關於new 和delete的重載。
?1、對照使用重載和未使用重載
?未使用“
/*File : operator_new.cpp *Auth : sjin *Date : 2014-04-27 *Mail : [email protected] */ #include <iostream> using namespace std; class test { public: test(){cout << "*****構造test()*****"<< endl;}; ~test(){cout << "+++++析構test()+++++"<< endl;}; }; int main() { test * x = new test;//運行分配空間，再運行析構函數 delete x;//先運行析構函數，在釋放空間 }
使用重載後，
/*File : operator_new.cpp *Auth : sjin *Date : 2014-04-27 *Mail : [email protected] */ #include <iostream> using namespace std; char mem[10000] = {‘\0‘}; int pos = 0; class test { public: test(){cout << "*****構造test()*****"<< endl;}; ~test(){cout << "+++++析構test()+++++"<< endl;}; public: void * operator new(size_t bytes){ cout << "------new test()------" << endl; int alloc = pos; pos += bytes; return (mem + alloc); }; void operator delete(void *){ cout << "------delete test()------" << endl; }; }; int main() { test * x = new test; delete x; }
/*File : operator_new.cpp *Auth : sjin *Date : 2014-04-27 *Mail : [email protected] */ #include <iostream> using namespace std; char mem[10000] = {‘\0‘}; int pos = 0; class test { public: test(){cout << "*****構造test()*****"<< endl;}; ~test(){cout << "+++++析構test()+++++"<< endl;}; public: void * operator new(size_t bytes){ cout << "------new test()------" << endl; int alloc = pos; pos += bytes; return (mem + alloc); }; void operator delete(void *){ cout << "------delete test()------" << endl; }; }; int main() { test * x = new test; delete x; x = new test[3]; delete [] x;//這裏對數組釋放，須要註意 }
#include <iostream>
using namespace std;
char mem[10000] = {‘\0‘};
int pos = 0;
class test {
public:
test(){cout << "*****構造test()*****"<< endl;};
~test(){cout << "+++++析構test()+++++"<< endl;};
public:
void * operator new(size_t bytes){
cout << "------new test()------" << endl;
int alloc = pos;
pos += bytes;
return (mem + alloc);
};
void operator delete(void *){
cout << "------delete test()------" << endl;
};
void * operator new[](size_t bytes){
cout << "------new test()------" << endl;
int alloc = pos;
pos += bytes;
return (mem + alloc);
};
void operator delete[](void *){
cout << "------delete test()------" << endl;
};
};
int main()
{
test * x = new test;
delete x;
x = new test[3];
delete [] x;
}對new 和delete 函數的重載能夠用來檢測 內存泄露的情況。
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走進C++程序世界-----operator new delete 重載