PathCanonicalizeW function (shlwapi.h)

Article
02/22/2024

Simplifies a path by removing navigation elements such as "." and ".." to produce a direct, well-formed path.

Note Misuse of this function can lead to a buffer overrun. We recommend the use of the safer PathCchCanonicalize or PathCchCanonicalizeEx function in its place.

Syntax

BOOL PathCanonicalizeW(
  [out] LPWSTR  pszBuf,
  [in]  LPCWSTR pszPath
);

Parameters

[out] pszBuf

Type: LPTSTR

A pointer to a string that receives the canonicalized path. You must set the size of this buffer to MAX_PATH to ensure that it is large enough to hold the returned string.

[in] pszPath

Type: LPCTSTR

A pointer to a null-terminated string of maximum length MAX_PATH that contains the path to be canonicalized.

Return value

Type: BOOL

Returns TRUE if a result has been computed and the content of the lpszDst output buffer is valid. Returns FALSE otherwise, and the contents of the buffer pointed to by lpszDst are invalid. To get extended error information, call GetLastError.

Remarks

This function allows the user to specify what to remove from a path by inserting special character sequences into the path. The ".." sequence indicates to remove a path segment from the current position to the previous path segment. The "." sequence indicates to skip over the next path segment to the following path segment. The root segment of the path cannot be removed.

If there are more ".." sequences than there are path segments, the function returns TRUE and contents of the buffer pointed to by lpszDst contains just the root, "".

Examples


#include <windows.h>
#include <iostream>
#include "Shlwapi.h"

using namespace std;

int main( void )
{
// Path_1 destination buffer.
char buffer_1[MAX_PATH] = "JustABufferToHoldTheCanonicalizedPathForAnExample";
char *lpStr1;
lpStr1 = buffer_1;

// Path_2 to be Canonicalized.
char buffer_2[ ] = "A:\\name_1\\.\\name_2\\..\\name_3";
char *lpStr2;
lpStr2 = buffer_2;

// Path_3 to be Canonicalized.
char buffer_3[ ] = "A:\\name_1\\..\\name_2\\.\\name_3";
char *lpStr3;
lpStr3 = buffer_3;

// Path_4 to be Canonicalized.
char buffer_4[ ] = "A:\\name_1\\name_2\\.\\name_3\\..\\name_4";
char *lpStr4;
lpStr4 = buffer_4;

// Path_5 to be Canonicalized.
char buffer_5[ ] = "A:\\name_1\\.\\name_2\\.\\name_3\\..\\name_4\\..";
char *lpStr5;
lpStr5 = buffer_5;

// Path_6 to be Canonicalized.
char buffer_6[ ] = "C:\\..";
char *lpStr6;
lpStr6 = buffer_6;

cout << "The un-canonicalized path 2 is : " << lpStr2
     << "\nThe return value is            : " 
     << PathCanonicalize(lpStr1,lpStr2)
     << "\nThe canonicalized path 1 is    : " << lpStr1 << endl;

cout << "\nThe un-canonicalized path 3 is : " << lpStr3
     << "\nThe return value is            : " 
     << PathCanonicalize(lpStr1,lpStr3)
     << "\nThe canonicalized path 1 is    : " << lpStr1 << endl;

cout << "\nThe un-canonicalized path 4 is : " << lpStr4
     << "\nThe return value is            : " 
     << PathCanonicalize(lpStr1,lpStr4)
     << "\nThe canonicalized path 1 is    : " << lpStr1 << endl;

cout << "\nThe un-canonicalized path 5 is : " << lpStr5
     << "\nThe return value is            : " 
     << PathCanonicalize(lpStr1,lpStr5) 
     << "\nThe canonicalized path 1 is    : " << lpStr1 << endl;

cout << "\nThe un-canonicalized path 6 is : " << lpStr6
     << "\nThe return value is            : " 
     << PathCanonicalize(lpStr1,lpStr6)
     << "\nThe canonicalized path 1 is    : " << lpStr1 << endl;
}
OUTPUT:
---------
The un-canonicalized path 2 is : A:\name_1\.\name_2\..\name_3
The return value is            : 1
The canonicalized path 1 is    : A:\name_1\name_3

The un-canonicalized path 3 is : A:\name_1\..\name_2\.\name_3
The return value is            : 1
The canonicalized path 1 is    : A:\name_2\name_3

The un-canonicalized path 4 is : A:\name_1\name_2\.\name_3\..\name_4
The return value is            : 1
The canonicalized path 1 is    : A:\name_1\name_2\name_4

The un-canonicalized path 5 is : A:\name_1\.\name_2\.\name_3\..\name_4\..
The return value is            : 1
The canonicalized path 1 is    : A:\name_1\name_2

The un-canonicalized path 6 is : C:\..
The return value is            : 1
The canonicalized path 1 is    : C:\

Note

The shlwapi.h header defines PathCanonicalize as an alias that 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 is 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, Windows XP [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	shlwapi.h
Library	Shlwapi.lib
DLL	Shlwapi.dll (version 4.71 or later)

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