Why does C++ allow an integer to be assigned to a string?

Question

I encountered an interesting situation today in a program where I inadvertantly assigned an unsigned integer to a std::string. The VisualStudio C++ compiler did not give an

Answer 1

It is definitely operator=(char ch) call - my debugger stepped into that. And my MS VS 2005 compiles following without error.

std::string my_string("");
unsigned int my_number = 1234;
my_string = my_number;
my_string.operator=(my_number);