_searchenv, _wsearchenv

Articolo
07/24/2011

Searches for a file using environment paths. More secure versions of these functions are available; see _searchenv_s, _wsearchenv_s.

void _searchenv(
   const char *filename,
   const char *varname,
   char *pathname 
);
void _wsearchenv(
   const wchar_t *filename,
   const wchar_t *varname,
   wchar_t *pathname 
);
template <size_t size>
void _searchenv(
   const char *filename,
   const char *varname,
   char (&pathname)[size]
); // C++ only
template <size_t size>
void _wsearchenv(
   const wchar_t *filename,
   const wchar_t *varname,
   wchar_t (&pathname)[size]
); // C++ only

Parameters

filename
Name of the file to search for.
varname
Environment to search.
pathname
Buffer to store the complete path.

Remarks

The _searchenv routine searches for the target file in the specified domain. The varname variable can be any environment or user-defined variable that specifies a list of directory paths, such as PATH, LIB, and INCLUDE. Because _searchenv is case-sensitive, varname should match the case of the environment variable.

The routine searches first for the file in the current working directory. If it does not find the file, it looks next through the directories specified by the environment variable. If the target file is in one of those directories, the newly created path is copied into pathname. If the filename file is not found, pathname contains an empty null-terminated string.

The pathname buffer should be at least _MAX_PATH characters long to accommodate the full length of the constructed path name. Otherwise, _searchenv might overrun the pathname buffer resulting in unexpected behavior.

_wsearchenv is a wide-character version of _searchenv; the arguments to _wsearchenv are wide-character strings. _wsearchenv and _searchenv behave identically otherwise.

If filename is an empty string, these functions return ENOENT.

If filename or pathname is a NULL pointer, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, these functions return -1 and set errno to EINVAL.

For more information about errno and error codes, see errno Constants.

In C++, these functions have template overloads that invoke the newer, secure counterparts of these functions. For more information, see Secure Template Overloads.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tsearchenv	_searchenv	_searchenv	_wsearchenv

Requirements

Routine	Required header
_searchenv	<stdlib.h>
_wsearchenv	<stdlib.h> or <wchar.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_searchenv.c
// compile with: /W3
// This program searches for a file in
// a directory specified by an environment variable.

#include <stdlib.h>
#include <stdio.h>

int main( void )
{
   char pathbuffer[_MAX_PATH];
   char searchfile[] = "CL.EXE";
   char envvar[] = "PATH";

   // Search for file in PATH environment variable:
   _searchenv( searchfile, envvar, pathbuffer ); // C4996
   // Note: _searchenv is deprecated; consider using _searchenv_s
   if( *pathbuffer != '\0' )
      printf( "Path for %s:\n%s\n", searchfile, pathbuffer );
   else
      printf( "%s not found\n", searchfile );
}

Path for CL.EXE:
C:\Program Files\Microsoft Visual Studio 8\VC\BIN\CL.EXE

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

Change History

Date	History	Reason
September 2010	Added a note about what happens if pathname is NULL.	Information enhancement.

September 2010

Added a note about what happens if pathname is NULL.

Information enhancement.

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