CODEWITHSUNDEEP
c++templates
Norhther
Norhther

Reputation: 500

Variadic template print implementation with separator

I'm trying to do a simple PoC with variadic templates. Right now, my code is as follows:

#include <iostream>
#include <string>
using namespace std;
template <typename T>
void println(const T& head) {
    cout << head << endl;
}

template <typename T, typename ... Args>
void println(const T& head, Args&& ... args) {
    cout << head << ", ";
    println(args...);
}

int main() {
    println(1,2,3,4,5,6);
}

Here, the separator is , , but I would like to be user provided, and also with a default value. However, trying something like void println(const T& head, const Args&... args, const string& sep = ",") is not going to work due the parameter pack. Is there any workaround to do this in a simple manner?

Upvotes: 0

Views: 453

Answers (1)

max66
max66

Reputation: 66230

I propose the following, non recursive, version. Based on a template defaulted value separator

#include <iostream>

template <char Sep = ',', typename T, typename ... Args>
void println (T const & head, Args const & ... args)
 { ((std::cout << head), ..., (std::cout << Sep << ' ' << args)) << std::endl; }

int main()
 {
   println(1,2,3,4,5,6);
   println<':'>(1,2,3,4,5,6);
 }

that prints

1, 2, 3, 4, 5, 6
1: 2: 3: 4: 5: 6

Upvotes: 5

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