CharPrevA function (winuser.h)

Article
02/22/2024

Retrieves a pointer to the preceding character in a string. This function can handle strings consisting of either single- or multi-byte characters.

Syntax

LPSTR CharPrevA(
  [in] LPCSTR lpszStart,
  [in] LPCSTR lpszCurrent
);

Parameters

[in] lpszStart

Type: LPCTSTR

The beginning of the string.

[in] lpszCurrent

Type: LPCTSTR

A character in a null-terminated string.

Return value

Type: LPTSTR

The return value is a pointer to the preceding character in the string, or to the first character in the string if the lpszCurrent parameter equals the lpszStart parameter.

Remarks

When called as an ANSI function, CharPrev uses the system default code-page, whereas CharPrevExA specifies a code-page to use.

This function works with default "user" expectations of characters when dealing with diacritics. For example: A string that contains U+0061 U+030a "LATIN SMALL LETTER A" + COMBINING RING ABOVE" — which looks like "å", will advance two code points, not one. A string that contains U+0061 U+0301 U+0302 U+0303 U+0304 — which looks like "a´^~¯", will advance five code points, not one, and so on.

Note

The winuser.h header defines CharPrev as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winuser.h (include Windows.h)
Library	User32.lib
DLL	User32.dll