CHString::FormatMessageW(LPCWSTR,...) method (chstring.h)

[The CHString class is part of the WMI Provider Framework which is now considered in final state, and no further development, enhancements, or updates will be available for non-security related issues affecting these libraries. The MI APIs should be used for all new development.]

The FormatMessageW method formats a message string.


void  throw(CHeap_Exception) FormatMessageW(
  LPCWSTR lpszFormat,



A pointer to the formal control string. The control string is scanned for inserts and formatted accordingly. The format string is similar to the runtime function, printf-style format strings, except that printf allows the parameters to be inserted in an arbitrary order.


Argument list.

Return value



The FormatMessageW method requires a message definition as input. The message definition is determined by lpszFormat, or from the string resource identified by nFormatID. The method copies the formatted message text to the CHString string, processing any embedded insert sequences if requested.

Each insert must have a corresponding parameter that follows the lpszFormat or nFormatID parameter. Within the message text, several escape sequences are supported for dynamically formatting the message. For more information and a description of these escape sequences and their meanings, see the FormatMessage function topic.

Note To reduce security vulnerability, always use a format string for FormatMessageW. For example, FormatMessageW(input) is exploitable, and FormatMessageW("%s", input) is not. Never use a user-supplied string for the format string. If your format string is stored for a purpose such as localization, ensure that the string is protected from unauthorized write access. If your function writes to a string rather than standard output, you may need to avoid using a trailing "%s" in the format string.


The following code example shows how to use CHString::FormatMessageW.

CHString str;
int nAsked = 5;
int nAgree = 4;

str.FormatMessageW(L"%1!d! of %2!d! developers agree: Golf is %3%!", 
                   nAgree, nAsked, L"Best");
assert(str == L"4 of 5 developers agree: Golf is Best!");


Requirement Value
Header chstring.h

See also