reduce characters from LPWSTR and save it as LPCWSTR

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Hello,
I have a string saved as LPWSTR.
I have to make a change in this string (reduce some characters) and save it as LPCWSTR.
How can i do it?

Thanks

Posted 30-Mar-11 6:54am

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Sergey Alexandrovich Kryukov · Answer 1 · 2011-03-30T07:29:00

Solution 1

You don't need any conversion from non-constant to constant string. Apparently, they are compatible in the assignment direction you want. Let's see:

C++

#include <windows.h>

//...

LPWSTR variable = L"my string";
variable[0] = 'M';
LPCWSTR constString = variable;

If you need to do the opposite, type cast is needed, because it would break the assumption on the string data being immutable. There are two ways:

C++

LPWSTR newString = (LPWSTR)constString;
LPWSTR newString2 = const_cast<LPWSTR>(constString);

—SA

Posted 30-Mar-11 7:29am

Sergey Alexandrovich Kryukov

Updated 30-Mar-11 7:36am

v4

Comments

Espen Harlinn 30-Mar-11 15:42pm

Good points, 5ed!

Sergey Alexandrovich Kryukov 30-Mar-11 17:04pm

Thank you, Espen. I guess that's all what involved.
--SA

Guyverthree 31-Mar-11 5:33am

Indeed they are the same for assignment purposes.

polaringu 3-Jun-11 5:16am

LPWSTR variable = L"my string";
variable[0] = 'M';

You can't do that, because you're changing the constant memory which is forbidden.
To do that you'll need to add a buffer, like so:
WCHAR buf[256] = L"my string"; //can be dynamic
LPWSTR variable = buf;
variable[0] = 'M';