Why can I assign an Int to a String without compiler error?

Question

All these lines compile and run, with nothing printed in the output:

  std::string ss{6}; 
  ss=7;
  std::cout << "ss " << ss << "\n";

I do not see any referenced constructor for std::string that would suggest it can coerce an integer to a string, so why does the compiler not complain?

Answer 1

The "problem" is that a std::string is assignable from char and int is implicitly convertible to char .

Take a look at std::basic_string::operator= point (4):

basic_string& operator=( CharT ch );

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EDIT

As stated in MM's comment , std::string ss{6}; calls the constructor taking initializer_list<char> (see std::basic_string::basic_string point (9) )... and the problem resurfaces.

Answer 2

It's the

basic_string& operator=( CharT ch );

So the int is implicitly being converted to a char .

Try assigning the value 65 . Prints A

Answer 3

The line ss=7 does not call a constructor, but the assignment operator =() .

std::string does have an assignment operator that takes a char , and your value 7 is converted into a char , then the string& operator= (char c); is called for that value. Your string will contain the ASCII BELL character.

See here for more info.