C++ ternary operator string concatenation

Question

I have seen this question asked for other languages, but not C++. Here's what I'm trying to do:

bool a = true;
string s;
s.append("a:" + (a? "true" : "false"));    
cout << s << endl;

I get a compiler error stating that I cannot add two pointers. What gives?

Answer 1

s.append(string("a:") + (a? "true" : "false"));

Answer 2

"true", "false", "a:", "b:" and "c:" are pointers (raw char arrays, actually). When you add them together with + (e.g. "a:" + "true") , then std::string is not involved, and it's only std::string which actually gives + the meaning of concatenation.

Here's what I do in such situations:

s += "a:" + std::string(a ? "true" : "false");