type deduction in template example

typede_duction_in_template.cpp

// ----------------------------------
// example 1
template<typename T>
void f(const T& param);

int x = 0;
const int cx = x;
const int& rx = x;
f(x);        // param is const int&
f(cx);       // param is const int&
f(rx);       // param is const int&

// ----------------------------------
// example 2
template<typename T>
void f(T& param);

int x = 0;
const int cx = x;
const int& rx = x;
f(x);        // param is int&
f(cx);       // param is const int&
f(rx);       // param is const int&

// ----------------------------------
// example 3
template<typename T>
void f(T* param);

int x = 27;
const int* px = &x;
f(&x);       // param is int*
f(px);       // param is const int*

// ----------------------------------
// example 4
template<typename T>
void f(T&& param);

int x = 27;
const int cx = x;
const int& rx = x;
f(x);        // param is int&
f(cx);       // param is const int&
f(rx);       // param is const int&
f(27);       // param is int&&

// ----------------------------------
// example 5
template<typename T>
void f(T param);

int x = 0;
const int cx = x;
const int& rx = x;
const char* const ptr = "hello world";
const char[] name = "Takkar";
f(x);        // param is int
f(cx);       // param is int
f(rx);       // param is int
f(ptr);      // param is const char* const
f(name);     // param is const char*

// ----------------------------------
// example 6
template<typename T>
void f(T& param);

const char[] name = "Takkar";
f(name);     // param is const char(&)[7]

// ----------------------------------
// example 7
template<typename T, std::size_t N>
constexpr std::size_t arraySize(T (&)[N]) noexcept
{
  return N;
}

const char[] name = "Takkar";
auto size = arraySize(name);    // size = 7.

// ----------------------------------
// example 8
void some(int, double);
template<typename T>
f1(T param);
template<typename T>
f2(T& param);

f1(some);      // param is void (*)(int, double)
f2(some);      // param is void (&)(int, double)