I need to merge a lot of strings into one. Something like this
stringstream ss;
string str_one = "hello ";
string str_two = "world!\n";
ss.add(str_one);
ss.add(str_two);
string result = ss.str();
but there is no add function into stringstream. How do I do this?
stringstream has operator<< overload to insert data into the stream. It would return a reference to the stream itself so you can chain multiple insertions.
ss << str_one << str_two;
std::cout << ss.str(); // hello world!
As an alternate, you can leverage fold expression(since C++17) to concatenate multiple strings.
template<typename ...T>
std::string concat(T... first){
return ((first+ ", ") + ...);
}
int main(){
std::string a = "abc", b = "def", c = "ghi", d = "jkl";
std::cout << concat(a, b, c, d); // abc, def, ghi,
}
The fold expression is expanded as below:
"abc" + ("def" + ("ghi" + "jkl"));
Very simple, all you have to do:
ss << " appended string";
You can use str() method like this:
std::string d{};
std::stringstream ss;
ss.str("hello this");
while(std::getline(ss, d)){
std::cout << d;
};
