FoldString

The FoldString function maps one string to another, performing a specified transformation option.

int FoldString(
  DWORD dwMapFlags,  // mapping transformation options
  LPCTSTR lpSrcStr,  // pointer to source string
  int cchSrc,        // size of source string, in bytes or characters
  LPTSTR lpDestStr,  // pointer to destination buffer
  int cchDest        // size of destination buffer, in bytes or characters
);
 

Parameters

dwMapFlags

A set of bit flags that indicate the type of transformation to be used during mapping. This value can be a combination of the following bit-flag constants:

Option	Meaning
MAP_FOLDCZONE	Fold compatibility zone characters into standard Unicode equivalents. For information about compatibility zone characters, see the following Remarks section.
MAP_FOLDDIGITS	Map all digits to Unicode characters 0 through 9.
MAP_PRECOMPOSED	Map accented characters to precomposed characters, in which the accent and base character are combined into a single character value. This value cannot be combined with MAP_COMPOSITE.
MAP_COMPOSITE	Map accented characters to composite characters, in which the accent and base character are represented by two character values. This value cannot be combined with MAP_PRECOMPOSED.
MAP_EXPAND_LIGATURES	Expand all ligature characters so that they are represented by their two-character equivalent. For example, the ligature 'æ' expands to the two characters 'a' and 'e'. This value cannot be combined with MAP_PRECOMPOSED or MAP_COMPOSITE.

lpSrcStr

Pointer to the string to be mapped.

cchSrc

Specifies the size, in bytes (ANSI version) or characters (Unicode version), of the lpSrcStr buffer. If cchSrc is –1, lpSrcStr is assumed to be null-terminated, and the length is calculated automatically.

lpDestStr

Pointer to the buffer to store the mapped string.

cchDest

Specifies the size, in bytes (ANSI version) or characters (Unicode version), of the lpDestStr buffer. If cchDest is zero, the function returns the number of bytes or characters required to hold the mapped string, and the buffer pointed to by lpDestStr is not used.

Return Values

If the function succeeds, the return value is the number of bytes (ANSI version) or characters (Unicode version) written to the destination buffer, or if the cchDest parameter is zero, the number of bytes or characters required to hold the mapped string.

If the function fails, the return value is zero. To get extended error information, call GetLastError. GetLastError may return one of the following error codes:

ERROR_INSUFFICIENT_BUFFER
ERROR_INVALID_FLAGS
ERROR_INVALID_PARAMETER

Remarks

The mapped string is null-terminated if the source string is null-terminated.

The lpSrcStr and lpDestStr pointers must not be the same. If they are the same, the function fails and GetLastError returns ERROR_INVALID_PARAMETER.

The compatibility zone in Unicode consists of characters in the range 0xF900 through 0xFFEF that are assigned to characters from other character-encoding standards but are actually variants of characters that are already in Unicode. The compatibility zone is used to support round-trip mapping to these standards. Applications can use the MAP_FOLDCZONE flag to avoid supporting the duplication of characters in the compatibility zone.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Unsupported.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winnls.h.
  Import Library: Use kernel32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also

String Manipulation Overview, String Manipulation Functions, LCMapString, CompareString