ms.workload: ["cplusplus"]

```

By using the Tchar.h, you can build single-byte, Multibyte Character Set (MBCS), and [!INCLUDE[TLA#tla_unicode](../atl-mfc-shared/reference/includes/tlasharptla_unicode_md.md)] applications from the same sources. Tchar.h defines macros (which have the prefix `_tcs`) that, with the correct preprocessor definitions, map to `str`, `_mbs`, or `wcs` functions, as appropriate. To build MBCS, define the symbol `_MBCS`. To build [!INCLUDE[TLA#tla_unicode](../atl-mfc-shared/reference/includes/tlasharptla_unicode_md.md)], define the symbol `_UNICODE`. To build a single-byte application, define neither (the default). By default, `_MBCS` is defined for MFC applications.

Because some Single Byte Character Set (SBCS) string-handling functions take (signed) `char*` parameters, a type mismatch compiler warning results when `_MBCS` is defined. There are three ways to avoid this warning:

|Generic-Text<br /><br /> Data Type Name|_UNICODE &<br /><br /> _MBCS Not Defined|_MBCS<br /><br /> Defined|_UNICODE<br /><br /> Defined|

|--------------------------------------|----------------------------------------|------------------------|---------------------------|

|`_T` or `_TEXT`|No effect (removed by preprocessor)|No effect (removed by preprocessor)|`L` (converts the following character or string to its [!INCLUDE[TLA#tla_unicode](../atl-mfc-shared/reference/includes/tlasharptla_unicode_md.md)] counterpart)|

For a list of generic-text mappings of routines, variables, and other objects, see [Generic-Text Mappings](../c-runtime-library/generic-text-mappings.md) in the Run-Time Library Reference.

}

```

Console::WriteLine("{0}", systemstring);

delete systemstring;

}

Console::WriteLine("{0}", systemstring);

delete systemstring;

}

}

```

Console::WriteLine("{0}", systemstringw);

delete systemstringw;

}

}

```

}

```

Most traditional C and C++ code makes assumptions about character and string manipulation that do not work well for international applications. While both MFC and the run-time library support Unicode or MBCS, there is still work for you to do. To guide you, this section explains the meaning of "international enabling" in Visual C++:

- Class library code uses portable run-time functions and other means to ensure correct Unicode or MBCS behavior.

- You still must handle certain kinds of internationalization tasks in your code:

- Use the same portable run-time functions that make MFC portable under either environment.

- Take precautions when parsing strings under MBCS. These precautions are not needed under Unicode. For more information, see [MBCS Programming Tips](../text/mbcs-programming-tips.md).

- Do not hard-code strings in your application. Instead, make them STRINGTABLE resources by adding them to the application's .rc file. Your application can then be localized without requiring source code changes or recompilation. For more information about STRINGTABLE resources, see [String Editor](../windows/string-editor.md).

[Unicode and MBCS](../text/unicode-and-mbcs.md)

You use MBCS-specific functionality. Strings can contain single-byte characters, double-byte characters, or both. The C run-time library provides functions, macros, and data types for MBCS-only programming. MFC is fully MBCS-enabled.

You use fully portable C run-time functions, macros, and data types. MFC's flexibility supports any of these strategies.

The memory window does not interpret bytes of data as MBCS characters, even though it can interpret them as ANSI or Unicode characters. ANSI characters are always 1 byte in size and Unicode characters are 2 bytes in size. With MBCS, characters can be 1 or 2 bytes in size and their interpretation depends on which code page is in use. Because of this, it is difficult for the memory window to reliably display MBCS characters. The memory window cannot know which byte is the start of a character. The developer can view the byte values in the memory window and look up the value in tables to determine the character representation. This is possible because the developer knows the starting address of a string based on the source code.

Applications written for East Asian markets that use MBCS (for example, Japan) normally support the Windows IME for entering both single- and double-byte characters. The Visual C++ development environment contains full support for the IME. For more information, see [IME Sample: Demonstrates How to Control IME Mode and Implement IME Level 3](http://msdn.microsoft.com/en-us/87ebdf65-cef0-451d-a6fc-d5fb64178b14).

MBCS characters in the environment

MBCS characters can appear in strings such as file and directory names.

In an application that uses MBCS, string handling poses special problems. Characters of both widths are mixed in a single string; therefore, you must remember to check for lead bytes.

The Mbctype.h and Mbstring.h header files define MBCS-specific functions and macros, which you might need in some cases. For example, `_ismbblead` tells you whether a specific byte in a string is a lead byte.