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2.3.cpp
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49 lines (37 loc) · 970 Bytes
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//
// 2.3.cpp
// c++1x tutorial
//
// created by changkun at shiyanlou.com
//
// auto/decltype/尾返回类型/返回类型推导
#include <iostream>
// 传统 C++
template <typename R, typename T, typename U>
R add1(T x, U y) {
return x+y;
}
// 尾返回类型
template <typename T, typename U>
auto add2(T x, U y) -> decltype(x+y) {
return x+y;
}
// C++14 返回类型推导
template <typename T, typename U>
auto add3(T x, U y) {
return x+y;
}
int main() {
auto i = 5;
int arr[10] = {0};
auto auto_arr = arr; // 正确，对整个类型进行推导
//auto auto_arr2[10] = arr; // 错误, 无法推导数组元素类型
auto x = 1;
auto y = 2;
decltype(x+y) z1;
//auto z2; // 错误, 无法推导
std::cout << add1<int, int, int>(1,1) << std::endl;
std::cout << add1<int, int>(1,1) << std::endl;
std::cout << add1<int, int>(1,1) << std::endl;
return 0;
}