A Magic Spell: Using auto and decltype in C++11 to Declare Objects Without Spelling Out Their TypesDanny Kalev
// and type of y is same as return type of fun2() decltype(fun1())x; decltype(fun2())y; cout<<typeid(x).name()<<endl; cout<<typeid(y).name()<<endl; return0; } 输出 i c 下面再举一个例子来演示decltype的使用, CPP实现 // C++ program to demonstrate use of decltype #include...
In this tutorial, we will be discussing a program to understand Type interference in C++ (auto and decltype). In the case of auto keyword, the type of the variable is defined from the type of its initializer. Further, with decltype, it lets you extract the type of variable from the ...
inta=3,b=4;decltype(a)c=a;// <=> int c = a; c 是int 型decltype(a=b)d=a;// <=>...
decltype关键字可以用于推导变量、表达式和函数返回值的类型。在推导变量类型时,可以使用decltype关键字加上变量名或表达式作为参数,编译器会根据变量或表达式的类型推导出变量的类型。 模板类型推导 C++中的auto是建立在模板类型推导的基础之上,如下所示一个函数模板:...
template<typenameContainer,typenameIndex>decltype(auto)authAndAccess(Container&c,Indexi);容器通过传...
decltype(ci) x = 0;// x has type const int decltype(cj) y = x;// y has type const int & and is bound to x decltype(cj) z;// error: z is a reference and must be initialized. 当表达式不是变量,而是可作为左值的对象时,那么decltype返回的时指向该对象类型的应用。
decltype(r+0) b;//ok: addition yields anint; b is an (uninitialized)intdecltype(*p) c;//error: c isint&andmust be initialized Here r is a reference, so decltype(r) is a reference type. If we want the type to which r refers, we can use r in an expression, such as r+0, ...
This is way better for the caller, and the template code loses nothing in readability--if anything, it's easier to understand! The joy of decltype and the new return value syntax Now you might be saying here--okay, that's great, but what if I wanted to *return* the value that this...
1.1 Changes from N1607 Changes to the previous revisions primarily reflect the EWG discussions and results of the straw votes that took place in the Kona and Sydney meetings. In addition, we suggest a change to the rules of decltype for certain built-in operators, and for expressions that ...