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suggest i have a template function like following:
template<class T> void doSomething() { T a; // a is correctly initialized if T is a class with a default constructor ... }; But variable a leaves uninitialized, if T is a primitive type. I can write T a(0), but this doesn't work if T is a class. Is there a way to initialize the variable in both cases (T == class, T == int, char, bool, ...)?
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A variable template may be introduced by a template declaration at namespace scope, where variable-declaration declares a variable. When used at class scope, variable template declares a static data member template.
" typename " is a keyword in the C++ programming language used when writing templates. It is used for specifying that a dependent name in a template definition or declaration is a type.
A class template must be declared before any instantiation of a corresponding template class. A class template definition can only appear once in any single translation unit. A class template must be defined before any use of a template class that requires the size of the class or refers to members of the class.
Templates in c++ is defined as a blueprint or formula for creating a generic class or a function. To simply put, you can create a single function or single class to work with different data types using templates. C++ template is also known as generic functions or classes which is a very powerful feature in C++.
Like so:
T a{}; Pre-C++11, this was the simplest approximation:
T a = T(); But it requires T be copyable (though the copy is certainly going to be elided).
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Class template field in C++11 has the same syntax:
template <class T> class A { public: A() {} A(T v) : val(v) {} private: T val{}; }; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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