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在下面的代碼我怎樣才能默認初始化靜態類模板變量
#include <iostream>
#include <string>
#include <type_traits>
template<class T, typename = std::enable_if<std::is_default_constructible<T>::value>>
struct E {
static T var;
};
int main() {
std::cout << E<std::string>::var << std::endl;
}
我怎麼能有E<T>::var
默認的E
每個模板實例構造?目前,我receiev鏈接錯誤
/home/tE1MjB/ccEXSZtn.o: In function `main':
prog.cpp:(.text.startup+0x12): undefined reference to `E<std::string, std::enable_if<true, void> >::var'
collect2: error: ld returned 1 exit status
爲什麼'{}'在初始化中? – shane
@shane:你可以在當前情況下忽略它們(因爲變量是靜態的),但我更喜歡[值初始化](http://en.cppreference.com/w/cpp/language/value_initialization)語法[默認初始化] (http://en.cppreference.com/w/cpp/language/default_initialization)語法 – Jarod42