Syntax for a variadic function template: :
template(typename arg, typename... args) return_type function_name(arg var1, args... var2) Note :, typename arg, typename... args must be inside angular brackets.
Below is an example in C++ to show how we can use variadic function template:
1 2 3.14 Pass me any number of arguments I will print I am empty function and I am called at last.
Remember that templates are replaced by actual functions by compiler.
The variadic templates work as follows :
The statement, print(1, 2, 3.14, “Pass me any number of arguments”, “I will print\n”); is evaluated in following manner :
Firstly, the compiler resolves the statement into
cout<< 1 <<endl ; print(2, 3.14, "Pass me any number of arguments", "I will print\n");
Now, the compiler finds a print() function which can take those arguments and in result executes the variadic print() function again in similar manner :
cout<< 2 <<endl ; print(3.14, "Pass me any number of arguments", "I will print\n");
Again, it is resolved into the following forms :
cout<< 3.14 <<endl ; print("Pass me any number of arguments", "I will print\n");
cout<< "Pass me any number of arguments" <<endl ; print("I will print\n");
cout<< "I will print\n" <<endl ; print();
Now, at this point the compiler searches for a function overload whose match is the empty function i.e. the function which has no argument.
This means that, all functions that have 1 or more arguments are matched to the variadic template and all functions that with no argument are matched to the empty function.
This article is contributed by MAZHAR IMAM KHAN. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.