析构函数 & 构造函数 C++



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​