charset encoding going from std::string to System::String and viceversa [modified]

[Andreoli Carlo]

Problem on charset encoding obj_db->query("UPDATE PATIENTS_DATA SET FIRST_NAME='flkسؤ' WHERE COD_PATIENT=2 "); give me a warning: 1>.\globalConfiguration.cpp(151) : warning C4566: character represented by universal-character-name '\u0633' cannot be represented in the current code page (1252) 1>.\globalConfiguration.cpp(151) : warning C4566: character represented by universal-character-name '\u0624' cannot be represented in the current code page (1252) and the real string in database is flk?? ----------edit----------- here i didn't pointed out the real problem...see my second post

modified on Thursday, October 15, 2009 6:14 AM

[Lost User]

barbetto80 wrote:

obj_db->query("UPDATE PATIENTS_DATA SET FIRST_NAME='flkسؤ' WHERE COD_PATIENT=2 ");

You have two Arabic characters at the end of the name, and the compiler is merely warning that the current code page does not support correct representation of them.

[Andreoli Carlo]

Ok now i pointed out exactly which is my problem :doh: ant it's a charset encoding going from std::string to System::String and viceversa: i query my database and i get the following string tmp_result_string= // in hexadecimal its value is C2 A3 then i convert using: String ^LAST_NAME=tmp_result_string.c_str(); when i set last_name_textBox->Text=LAST_NAME; the visual representation i get in the form is £ which is the ANSII encoding of C2 A3, but what i want is the textbox to display £ which is the utf8 encoding of C2 A3...any help? tha same problem i have doing the inverted thing getting text from textbox and putting it on database.

modified on Thursday, October 15, 2009 9:22 AM

[Andreoli Carlo]

ok..i find answer to the problem: String^ databaseManagedWrapper::unMarshalStringUTF8(string %os) { char const* buffer = os.c_str(); cli::array<System::Byte>^ a = gcnew cli::array<System::Byte>(os.length()); int i = os.length(); while (i-- > 0) { a[i] = buffer[i]; } return System::Text::Encoding::UTF8->GetString(a); } now i need the inverse... string databaseManagedWrapper::MarshalStringUTF8( String ^ s) { System::Text::UTF8Encoding^ utf8 = gcnew System::Text::UTF8Encoding; array<Byte>^encodedBytes = utf8->GetBytes(s); string os=""; for (int i=0;i<encodedBytes->Length;i++) { os+=encodedBytes[i]; } return os; }

modified on Thursday, October 15, 2009 9:19 AM

[N a v a n e e t h]

System::String is Unicode compatible. You don't need to do any encoding here. Also I think your databaseManagedWrapper::unMarshalStringUTF8 function's implementation is wrong. Here is a version that converts string contains Unicode characters to System::String. std::wstring is used instead of std::string.

String^ UnicodeNativeStringToManagedString(wstring& os)
{
const wchar_t* buffer = os.c_str();
return gcnew String(buffer);
}

Here is the function for inverse. You need to work with methods in the Marshal class.

std::wstring UnicodeManagedStringToNative(String^ str)
{
using namespace System::Runtime::InteropServices;
wchar_t* chr = (wchar_t*) Marshal::StringToHGlobalAnsi(str).ToPointer();
std::wstring result(chr);
Marshal::FreeHGlobal(IntPtr(chr));
return result;
}

:)

Best wishes, Navaneeth

[Andreoli Carlo]

preamble: i'am using a database that can use UTF8 as best support for multi-language, so i started out from it. UTF8 is a variable-length character encoding for Unicode. The wrapper for the database id written in c++ and uses std::string as variables input method. Well my problem is that i need a std::string to store to the DB, and not wstring... that's why i create these methods. Maybe i didn't get your help as i see you are creating a wstring... ps thank you i really appreciate your answer to my various problem in this forum. You are helping me growing up learning and skilling this language

[N a v a n e e t h]

Well, its easy to convert my code to support std::string. You need char* instead if wchar_t*. Windows uses wchar_t for Unicode and it is 2 bytes wide with UTF-16 encoding. So when programming on windows, it is a better to use wchar_t. wstring is a typedef for basic_string templated using wchar_t. However, I tried to convert a UTF-8 encoded string to and from managed code. But it never worked until I changed to wstring. Perhaps I may need to investigate more. :)

Best wishes, Navaneeth