explicit keyword [duplicate]

This question already has answers here: 开发者_开发知识库 Closed 12 years ago.

Possible Duplicate:

What does the explicit keyword in C++ mean?

what does the keyword explicit mean?

---

C++ constructors that have just one parameter automatically perform implicit type conversion. For example, if you pass an int when the constructor expects a string pointer parameter, the compiler will add the code it must have to convert the int to a string pointer. However, you might not always want this automatic behavior.

You can add explicit to the constructor declaration to prevent implicit conversions. This forces the code to either use a parameter of the correct type, or cast the parameter to the correct type. That is, if the cast is not visibly expressed in code, an error will result.

explicit (C++)