CString to TCHAR

Question

Today after a long time I've seen this conversion:

void SomeFunction( LPCTSTR szText ) ...


CString str;
str.Format( "A Simple Sentence" );
SomeFunction( LPCTSTR( str ) );

It compiles OK. Any explanations about this conversion?

It seems mostly ok, because I don't need to use GetBuffer and release it later, nor create a new LPTSTR with the length of the string.

Answer 1

Yes this is OK, since CString has conversion operator to LPCTSTR. reference to operator

msdn

The C++ compiler automatically applies the conversion function defined for the CString class that converts a CString to an LPCTSTR.

So, you don't need use explicitly conversion to LPCTSTR.

Answer 2

Yes this is OK. According to the documentation you just need to make sure that you don't modify the string during the duration of the returned pointer, which your code is doing fine.

This is basically the CString equivalent of std::string::c_str().

Usually though you don't need to explicitly use the cast as your code does. The only reason I can think you need to do that is if you're converting to yet another type, for example if SomeFunction is defined as

void SomeFunction(const std::basic_string<TCHAR>& str);

In that case there is no implicit conversion from CString to std::basic_string<TCHAR> so you need to use LPCTSTR as an in-between.