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Exceptions
When used sparingly and with care, implicit conversions can make calling code short and intuitive. The standard std::string defines an implicit constructor that takes a const char* . This works fine because the designers took some precautions:Item 29). This avoids the creation of hidden temporary variables.
Even so, there can still be some weirdness with overloaded functions:void Display( int );
void Display( std::string );
Display( NULL ); // calls Display(int)
This result might be surprising. (Incidentally, if it did call Display( std::string ) , the code would have exhibited undefined behavior because it's illegal to construct a std::string from a null pointer, but its constructor isn't required to check for the null.)
