int puts ( const char * str );
#include <iostream>
#include <string>
using namespace std;
int main() {
// string str1 = "Hello\nworld"; // cannot convert argument 1 from 'std::string' to 'const char *'
char str1[] = "Hello\nworld";
puts(str1);
/*
* Hello
* world
*/
return 0;
}