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析构函数 & 构造函数

C++

析构函数(destructor) 与构造函数相反，当对象结束其生命周期，如对象所在的函数已调用完毕时，系统自动执行析构函数。
析构函数往往用来做“清理善后” 的工作（例如在建立对象时用new开辟了一片内存空间，delete会自动调用析构函数后释放内存）。

// spec1_destructors.cpp
#include <string>

class String {
public:
   String( char *ch );  // Declare constructor
   ~String();           //  and destructor.
private:
   char    *_text;
   size_t  sizeOfText;
};

// Define the constructor.
String::String( char *ch ) {
   sizeOfText = strlen( ch ) + 1;

   // Dynamically allocate the correct amount of memory.
   _text = new char[ sizeOfText ];

   // If the allocation succeeds, copy the initialization string.
   if( _text )
      strcpy_s( _text, sizeOfText, ch );
}

// Define the destructor.
String::~String() {
   // Deallocate the memory that was previously reserved
   //  for this string.
   delete[] _text;
}

int main() {
   String str("The piper in the glen...");
}

refs

https://docs.microsoft.com/zh-cn/cpp/cpp/destructors-cpp?view=vs-2019

https://www.runoob.com/cplusplus/cpp-constructor-destructor.html

https://www.cnblogs.com/mr-wid/archive/2013/02/19/2917911.html

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