#include using namespace std; template T max3(T a, T b, T c){ return (a < c && b < c) ? c : (a < b) ? b : a; } template auto sum3(T1 a1, T2 a2, T3 a3) -> decltype(a1 + a2 + a3){ return a1 + a2 + a3; } template auto sum2(T1 a, T2 b){ // Since C++14 auto without decltype is sufficent. return a + b; } //fold expressions since c++17 template void print(Args... a){ (cout << ... << a) << endl; } template auto sum(Args... a){ return (... + a); } template constexpr T pi = T(3.14159265); //specialization template<> constexpr const char* pi = "π"; int main(){ cout << "max : " << max3(3,1,4) << endl; cout << "max : " << max3(3.14f, 20.20f, 12.2f) << endl; cout << "max : " << max3('a', 'b', 'c') << endl; cout << "max double: " << max3(4, 3.14f, 30) << endl; auto s1 = sum3(1,2,3); cout << "sum3: " << s1 << typeid(s1).name() << endl; auto s2 = sum3(1, 2.0, 3.14f); cout << "sum3:" << s2 << typeid(s2).name() << endl; auto s3 = sum2(1, 2); auto s4 = sum2(3.14, 1); cout << "sum2: " << s3 << endl; cout << "sum2: " << s4 << endl; print(1,2,3,4,5); cout << "sum(10, 10, 20, 30, 3.2) = " < << endl; cout << "double: " << pi << endl; cout << pi << " = " << pi << endl; return 0; }

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