What is the BigO time complexity of modifying a string in C++?

Question

What is the runtime of modifying a std::string? I assume constant time or is there something more going on under the hood in the string class?

#include <string>

int main() {
  std::string str = "Hello World!"
  str[1] =  'a';  // <--- what is the runtime?
}

Cheers

Answer 1

That's right, it's constant. According to this:

Complexity

Constant.

For C++11 that is, it's unspecified for C++98, but I wouldn't assume that an implenetation with non-constant std::string::operator[] would be commonplace.