References

• https://en.cppreference.com/w/cpp/language/templates
• We will be studing about only function templates and abbreviated function template using keyword 'auto' which is also explained in above link(auto is just c++20 feature).

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Main points

• Templates have been introduced in 1991.
• we use templates like:

  		template <typename/class T>  //we can use the keywords typename or class 
  		T function_name(T parameter_names) // scope of T is within the function only. 
  		{
  
  		}
  

• we can use template using keyword auto which is just c++20 feature only.(compile with -std = c++20 )

  		auto function_name(auto parameter_names)
  		{
  		// function body; note that 'auto' will deduce the type for us. 	
  		}
  

#include<iostream>
auto multiply(auto a, auto b)
{
return a*b;
}

int main()
{
int a=2,b=4;
float c=2.5,d=2;
std::cout<<multiply(a,b)<<"\t"<<multiply(c,d)<<std::endl;
return 0;
}

Output
8 5

• Instantiation

It is process of making codes by compiler, In previous lecture 1 we saw that the compiler was make codes for us, and that is known as Instantiation.