How to concatenate a std::string and an int?

Question

I thought this would be really simple but it\'s presenting some difficulties. If I have

std::string name = \"John\";
int age = 21;

How do I

Answer 1

If you'd like to use + for concatenation of anything which has an output operator, you can provide a template version of operator+:

template  std::string operator+(L left, R right) {
  std::ostringstream os;
  os << left << right;
  return os.str();
}

Then you can write your concatenations in a straightforward way:

std::string foo("the answer is ");
int i = 42;
std::string bar(foo + i);    
std::cout << bar << std::endl;

Output:

the answer is 42

This isn't the most efficient way, but you don't need the most efficient way unless you're doing a lot of concatenation inside a loop.