pointer to a constant string

[bkelly13]

Windows 7, visual Studio 2008, C++

WCHAR *op_type = NULL;
if( x )
op_type = &L"First";
else
op_type = &L"Second";

This solicits the error

Quote:

error C2440: '=' : cannot convert from 'const wchar_t (*)[6]' to 'WCHAR *'

What is my syntax error? I tried the declaration:

const wchar_t *op_type2 = NULL;

and received the error:

Quote:

error C2440: '=' : cannot convert from 'const wchar_t (*)[6]' to 'const wchar_t *'

Which seems wrong to me. Why does the pointer care how long the string is? It is but the address of the first character.

Thank you for your time If you work with telemetry, please check this bulletin board: www.irigbb.com

[_Superman_]

For the first part of your question, you do not need the & sign.

WCHAR *op_type = NULL;
if( x )
op_type = L"First";
else
op_type = L"Second";

For the second part of your question, you should not be getting any errors. It is a valid statement.

«_Superman_»  _I love work. It gives me something to do between weekends.

_Microsoft MVP (Visual C++) (October 2009 - September 2013)

Polymorphism in C

[bkelly13]

Lets see if I really understand what you told me. The declaration:

const WCHAR *op_type = NULL;

was good. The use:

op_type = &L"Shutdown";

was incorrect. The declaration of the constant string:

&L"Shutdown";

is effectively a WCHAR array. Arrays are always passed by address so adding the & symbol was creating an pointer to a pointer. The error message:

Quote:

error C2440: '=' : cannot convert from 'const wchar_t (*)[9]' to 'const WCHAR *'

was telling me that but I was too wrapped up in reading the [9] as a length rather than an indicator that this is an array and the address is passed rather than the value. Thank you for helping me with this.

Thank you for your time If you work with telemetry, please check this bulletin board: www.irigbb.com

[leon de boer]

You logic is flawed but your result is correct. The "L" prefix is a sort of precompiler literal Microsoft has put in place it's not a macro or such and it is sort of bound like the quotes are in the precompiler look at how you write a normal string constants const char* txtcnst = "SOME_CONSTANT_TEXT"; There is no "&" pointer there so why just because you want a unicode string would they change it The answer is it is the way it is because that is how C language defined the use of constants and think of L as part of the quotes "" simply telling the compiler the text is unicode format.

In vino veritas

[CPallini]

As far as I know L is not a Microsoft thing, see, for instance "string literal" at cppreference.com[^].

Veni, vidi, vici.