C + + conversion constructors and type conversion functions

Look at the STL source, there is a piece of code feel very strange

return (Link_type) ((*node). Next); }

Iterator and Link_type are two different types, how can they return? Turning over the previous note, it was discovered that a temporary object was generated by the conversion constructor and then return.

The function of a conversion constructor is to convert some type of data into an object of a class, which is called a transform constructor when a constructor has only one parameter and is not a const reference to this class. Tried a little bit.

classa{ Public:    intA; A (inta): A (a) {} a Reta () {returnA; }};intMain () {A A (2); A b=A.reta (); A C=3; cout<<b.a<<"\ n"<<c.a<<Endl; return 0;}

The result is output 2 and 3

This is actually caused by the implicit conversion mechanism, and if you do not want this effect, you can add the explicit declaration before the constructor. Plus the code above will compile an error, prompting

Cannot convert from "int" to "A".

Since the data can be converted to a type, the type can also be converted to data. C + + type Conversion functions can convert an object of a class to a specified type of data.

The general form of a type conversion function is: operator type name () {implement translated statement} test code:

classa{ Public:    intA; A (inta): A (a) {}operator int()    {        returnA; }};intMain () {A A (2); intb = A +3; A C= A +4; cout<<b<<"\ n"<<c.a<<Endl; return 0;}

Result outputs 5 and 6

C + + conversion constructors and type conversion functions