SHUnicodeToAnsi function (shlwapi.h)

Article
10/13/2021

[This function is available through Windows XP and Windows Server 2003. It might be altered or unavailable in subsequent versions of Windows.]

Converts a string from the Unicode code page to the ANSI code page.

Syntax

int SHUnicodeToAnsi(
  [in]  PCWSTR pwszSrc,
  [out] PSTR   pszDst,
        int    cchBuf
);

Parameters

[in] pwszSrc

Type: PCWSTR

A pointer to the null-terminated Unicode string to be converted to ANSI.

[out] pszDst

Type: PSTR

A pointer to a buffer that, when this function returns successfully, receives the converted characters. The buffer must be large enough to contain the number of CHAR characters specified by the cchBuf parameter, including room for a terminating null character.

cchBuf

Type: int

The number of CHAR values that can be contained by the buffer pointed to by pszDst. The value assigned to parameter must be greater than zero.

Return value

Type: int

Returns the number of CHAR values written to the output buffer, including the terminating null character. Returns 0 if unsuccessful.

Remarks

Security Warning: Using this function incorrectly can compromise the security of your application. For example, if pszDst buffer is not large enough to contain the number of characters specified by cchBuf, a buffer overrun can occur. Buffer overruns can cause a denial of service attack against an application if an access violation occurs. In the worst case, a buffer overrun might allow an attacker to inject executable code into your process, especially if pszDst is a stack-based buffer. In addition, the output string is silently truncated if it is too large for the buffer. This can cause canonicalization or other security vulnerabilities.

If the pszDst buffer is not large enough to contain the entire converted output string, the string is truncated to fit the buffer. There is no way to detect that the return string has been truncated. The string will always be null-terminated, even if it has been truncated. This function takes care to not truncate between the lead and trail bytes of a DBCS character pair. In that case, only cchBuf-1 characters are returned.

If the pwszSrc and pszDst buffers overlap, the function's behavior is undefined.

Note Do not assume that the function has not changed any of the characters in the output buffer that follow the string's terminating null character. The contents of the output buffer following the string's terminating null character are undefined, up to and including the last character in the buffer.

SHTCharToAnsi is defined to be the same as SHUnicodeToAnsi.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional, Windows XP [desktop apps only]
Minimum supported server	Windows 2000 Server, Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	shlwapi.h
DLL	Shlwapi.dll (version 5.0 or later)