#include <stdio.h>

template <typename T>

constexpr T pi = T(3.123456789);

void test_1() {

int iPi = pi<int>;

float fPi = pi<float>;

double dPi = pi<double>;

printf("%d\n", iPi);

printf("%f\n", fPi);

printf("%E\n", dPi);

}

/////////////////////////////////////////////////////////////////////////////////

// Function template using variable template -

// From https://en.cppreference.com/w/cpp/language/variable_template

/////////////////////////////////////////////////////////////////////////////////

// Function template

template<class T>

T get2Pi(T r)

{

return pi<T> * 2; // pi<T> is a variable template instantiation

}

void test_2() {

int iPi;

float fPi;

double dPi;

iPi = get2Pi(iPi);

fPi = get2Pi(fPi);

dPi = get2Pi(dPi);

printf("%d\n", iPi);

printf("%f\n", fPi);

printf("%E\n", dPi);

}

/////////////////////////////////////////////////////////////////////////////////

// Additional from Pluralsight - Practical C++14/C++17 by Giovanni Dicanio

/////////////////////////////////////////////////////////////////////////////////

template <typename T>

constexpr T maxValue = T(1000);

// Template specializations

template <>

constexpr double maxValue<double> = 2000;

template <>

constexpr char maxValue<char> = 'Z';

void test_3() {

printf(" maxValue<int> = %d\n", maxValue<int>);

printf(" maxValue<double> = %f\n", maxValue<double>);

printf(" maxValue<char> = %c\n", maxValue<char>);

}

int main() {

test_1();

test_2();

test_3();

return 0;

}