如果类型转换失败，对于指针类型，则会返回空指针，对于引用类型则会抛出异常std::bad_cast（因为有空指...
int i = static_cast<int>(d); 但static_cast已经有安全性的考虑了,比如对于不相关类指针之间的转换。参见下面的例子: // class type-casting #include <iostream> using namespace std; class CDummy { float i,j; }; class CAddition { int x,y; public: CAddition (int a, int b) { x=a; y...
#include<iostream>#include<memory>using namespace std;voidCheck(weak_ptr<int>&wp){shared_ptr<int>sp=wp.lock();//获得shared_ptr<int>实例if(sp!=nullptr)cout<<"still "<<*sp<<endl;elsecout<<"pointer is invalid."<<endl;}intmain(){shared_ptr<int>sp1(newint(40));shared_ptr<int>sp2=...
{// NB: Not required, but considered best practice.if(__gnu_cxx::__is_null_pointer(__beg) && __beg != __end)std::__throw_logic_error(__N("basic_string::""_M_construct null not valid")); size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));if(__...
// C5054.cpp// Compile using: cl /EHsc /W4 /std:c++latest C5054.cppenumE1 { a };enumE2 { b };intmain(){inti = a | b;// warning C5054: operator '|': deprecated between enumerations of different types} 若要避免警告,請使用static_cast(部分機器翻譯) 來轉換第二個運算元: ...
char charArray[ITEMS]={'F','a','n','g','c'};int *intPtr=intArray;char *charPtr=charArray;std::cout<<"整型数组输出:"<<'\n';for(int i=0;i<ITEMS;i++){std::cout<<*intPtr<< "at"<<reinterpret_cast<unsigned long>(intPtr)<<'\n';intPtr++;}std::cout<<"字符型数组输出:...
. You can use it for more than just casting downwards -- you can cast sideways or even up another chain. Thedynamic_castwill seek out the desired object and return it if possible. If it can't, it will returnnullptrin the case of a pointer, or throwstd::bad_castin the case of a...
指向常量的指针(pointer to const) 自身是常量的指针(常量指针,const pointer) 引用 指向常量的引用(reference to const) 没有const reference,因为引用本身就是 const pointer (为了方便记忆可以想成)被 const 修饰(在 const 后面)的值不可改变,如下文使用例子中的 p2、p3。
在类层次上进行转换的时候 dynamic_cast于static_cast的效果一样! 他返回一个新类型的值,或者会抛出一个异常! 来看代码: #include<iostream> using namespace std; struct V { virtual void f() {}; // must be polymorphic to use runtime-checked dynamic_cast ...
在Visual Studio 2019 中,basic_string 範圍建構函式不再使用 static_cast 隱藏編譯器診斷。 在 Visual Studio 2017 中,下列程式碼在編譯時不會發出警告,但在初始化 out 時,從 wchar_t 到char 可能會遺失資料:C++ 複製 std::wstring ws = /* . . . */; std::string out(ws.begin(), ws.end())...