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Stack based path conversion.

, 6 Apr 2007
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The following article explains a stack based method to convert absolute path to relative and vice versa.

Introduction

The following article explains a simple algorithm to convert absolute path to relative and relative to absolute. Sample code also can be found along with the article. This code can be used free of cost but at your on risk. (Test the functions properly before using.)

The code works for windows as well as Linux. A description of the algorithm is given below.

Absolute path to relative path (Abs2Rel)

Abs2Rel path function takes absolute path as input and returns relative path.

//------------------------------------------------------------------------------
// Method        : Abs2Rel
// Description        : Convert absolute path to relative path.
// Parameter        : pcAbsPath - Input - Absolute path
// Parameter        : pcRelPath - Output - Relative path
// Parameter        : pcCurrDir - Input - Current Dir/Reference dir path
// Return        : Relative path
// Author        : Boby Thomas Pazheparampil April 2006
//------------------------------------------------------------------------------
char * Abs2Rel(char *pcAbsPath, char *pcRelPath, char* pcCurrDir)

Operation.

Following sequence will explain the conversion process.

For example consider the abs path "/cygdrive/d/boby/india/boby.txt", and reference directory "/cygdrive/d/try/path_conv"

Step 1: First extract the path parameters into stacks.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

boby.txt

india

path_conv

boby

try

d

d

cygdrive

cygdrive

Step 2: Push the size difference of stacks into output stack. If the absolute path stack size is more, push the actual content of the stack "tmpStackAbsPath" into the stack "tmpStackOutput". If the size of the stack "tmpStackCurrPath" is more, add an ellipse ("..") into output path "pcRelPath".

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

india

path_conv

boby

try

d

d

cygdrive

cygdrive

boby.txt

Step 3: Compare the tops of stacks "tmpStackAbsPath" and "tmpStackCurrPath". If it is matching, add into queue for later possible use. (If there is a mismatch in lower layers of stack, this queue will be used). If it is not matching like in the example above, contents of queue will be pushed to output stack. After pushing queue to "tmpStackOutput", top of "tmpStackAbsPath" will be pushed to stack "tmpStackOutput". Also an ellipse will be added to "pcRelPath", the output relative path.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

boby

try

d

d

india

cygdrive

cygdrive

boby.txt

pcRelPath = "..\"

Step 4: Repeat the same process till the end of stacks.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

boby

D

d

india

cygdrive

cygdrive

boby.txt

pcRelPath = "..\..\"

Step 5: Repeat the same process till the end of stacks.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

d

boby

india

cygdrive

cygdrive

boby.txt

pcRelPath = "..\..\"

Step 6: Repeat the same process till the end of stacks.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

cygdrive

d

boby

india

boby.txt

pcRelPath = "..\..\"

Step 7: Once the "tmpStackAbsPath" and "tmpStackCurrPath" are exhausted, move the content of "tmpStackOutput" to the output string pcRelPath .

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

cygdrive

d

india

boby.txt

pcRelPath = "..\..\boby\"

Step 8: Once the "tmpStackAbsPath" and "tmpStackCurrPath" are exhausted, move the content of "tmpStackOutput" to the output string pcRelPath .

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

cygdrive

d

boby.txt

pcRelPath = "..\..\boby\India\"

Step 9: Continue the process till the "tmpStackOutput" exhausts.

tmpStackAbsPath tmpStackCurrPath tmpStackOutput tmpMatchQueue

cygdrive

d

pcRelPath = "..\..\boby\india\ boby.txt"

Relative path to absolute path (Rel2Abs)

Abs2Rel path function takes absolute path as input and returns relative path.

//------------------------------------------------------------------------------
// Method        : Rel2Abs
// Description    : Convert absolute path to relative path.
// Parameter    : pcRelPath - Input - Relative path
// Parameter    : pcAbsPath - Output - Absolute path
// Parameter    : pcCurrDir - Input - Current Dir/Reference dir path
// Return        : Absolute path
// Author        : Boby Thomas Pazheparampil April 2006
//------------------------------------------------------------------------------

char * Rel2Abs(char *pcRelPath, char *pcAbsPath, char* pcCurrDir)

Operation.

Following sequence will explain the conversion process.

For example consider the relative path "../../boby/../temp.txt" and reference directory "/cygdrive/d/try/path_conv"

Step 1: First extract the relative path into queue "tmpQueueRelPath".

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

..

boby

..

..

Step 2: Then convert the reference path into stack "tmpStackCurrPath".

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

..

boby

..

path_conv

..

try

d

cygdrive

Step 3: Take entries from the front of the queue "tmpQueueRelPath". If it is an ellipse, pop out the last entry in the stack "tmpStackCurrPath". If the front entry in the queue "tmpQueueRelPath" is not ellipse, push the entry into stack "tmpStackCurrPath".

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

..

boby

..

try

d

cygdrive

Step 4: Continue the same process until the queue "tmpQueueRelPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

..

boby

d

cygdrive

Step 5: Continue the same process until the queue "tmpQueueRelPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

..

boby

d

cygdrive

Step 6: Continue the same process until the queue "tmpQueueRelPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

d

cygdrive

Step 7: Continue the same process until the queue "tmpQueueRelPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

d

cygdrive

Step 8: Once the queue "tmpQueueRelPath" exhausts, pop the content of the stack "tmpStackCurrPath" and push it to the stack "tmpStackOutput".

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

d

cygdrive

temp.txt

Step 9: Repeat the process till the stack "tmpStackCurrPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

d

cygdrive

temp.txt

Step 10: Repeat the process till the stack "tmpStackCurrPath" exhausts.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

cygdrive

d

temp.txt

Step 11: Once the stack "tmpStackCurrPath" is empty, take the content into absolute return path string.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

d

temp.txt

pcAbsPath = "/cygdrive/"

Step 12: Repeat the process till stack "tmpStackOutput" is empty.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

temp.txt

pcAbsPath = "/cygdrive/d/"

Step 13: Repeat the process till stack "tmpStackOutput" is empty.

tmpQueueRelPath tmpStackCurrPath tmpStackOutput

pcAbsPath = "/cygdrive/d/ temp.txt"

Summary

We can think of lots of different methods for the above implementation. Feedback about this method will be greatly appreciated. Contact me at bobypt@gmail.com.

 

 

 

 

 

 

 

 

 

 

boby

 

 

D

 

d

 

india

 

 

cygdrive

 

cygdrive

 

boby.txt

 

 

 

pcRelPath  = “..\..\”

 

Step 5: Repeat the same process till the end of stacks.

 

tmpStackAbsPath                tmpStackCurrPath                  tmpStackOutput                    tmpMatchQueue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

boby

 

 

 

 

 

 

india

 

 

cygdrive

 

cygdrive

 

boby.txt

 

 

 

pcRelPath  = “..\..\”

 

Step 6: Repeat the same process till the end of stacks.

tmpStackAbsPath                tmpStackCurrPath                  tmpStackOutput                    tmpMatchQueue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cygdrive

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

boby

 

 

 

 

 

 

india

 

 

 

 

 

 

boby.txt

 

 

 

pcRelPath  = “..\..\”

 

Step 7: Once the “tmpStackAbsPath” and “tmpStackCurrPath” are exhausted, move the content of “tmpStackOutput” to the output string pcRelPath .

tmpStackAbsPath                tmpStackCurrPath                  tmpStackOutput                    tmpMatchQueue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cygdrive

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

india

 

 

 

 

 

 

boby.txt

 

 

 

pcRelPath  = “..\..\boby\”

 

Step 8: Once the “tmpStackAbsPath” and “tmpStackCurrPath” are exhausted, move the content of “tmpStackOutput” to the output string pcRelPath .

 

tmpStackAbsPath                tmpStackCurrPath                  tmpStackOutput                    tmpMatchQueue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cygdrive

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

boby.txt

 

 

 

pcRelPath  = “..\..\boby\India\”

Step 9: Continue the process till the “tmpStackOutput” exhausts.

 

tmpStackAbsPath                tmpStackCurrPath                  tmpStackOutput                    tmpMatchQueue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cygdrive

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

pcRelPath  = “..\..\boby\india\ boby.txt”

 

 

Relative path to absolute path (Rel2Abs)

Abs2Rel path function takes absolute path as input and returns relative path.

//------------------------------------------------------------------------------
// Method        : Rel2Abs
// Description    : Convert absolute path to relative path.
// Parameter    : pcRelPath - Input - Relative path
// Parameter    : pcAbsPath - Output - Absolute path
// Parameter    : pcCurrDir - Input - Current Dir/Reference dir path
// Return        : Absolute path
// Author        : Boby Thomas Pazheparampil April 2006
//------------------------------------------------------------------------------

char * Rel2Abs(char *pcRelPath, char *pcAbsPath, char* pcCurrDir)

Operation.

            Following sequence will explain the conversion process.

For example consider the relative path “../../boby/../temp.txt" and reference directory “/cygdrive/d/try/path_conv”

 

Step 1: First extract the relative path into queue “tmpQueueRelPath”.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

..

 

 

 

 

boby

 

 

 

 

..

 

 

 

 

..

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 2: Then convert the reference path into stack “tmpStackCurrPath”.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

..

 

 

 

 

boby

 

 

 

 

..

 

path_conv

 

 

..

 

try

 

 

 

 

d

 

 

 

 

cygdrive

 

 

 

Step 3: Take entries from the front of the queue “tmpQueueRelPath”. If it is an ellipse, pop out the last entry in the stack “tmpStackCurrPath”. If the front entry in the queue “tmpQueueRelPath” is not ellipse, push the entry into stack “tmpStackCurrPath”.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

..

 

 

 

 

boby

 

 

 

 

..

 

 

 

 

 

 

try

 

 

 

 

d

 

 

 

 

cygdrive

 

 

 

Step 4: Continue the same process until the queue “tmpQueueRelPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

..

 

 

 

 

boby

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

cygdrive

 

 

 

Step 5: Continue the same process until the queue “tmpQueueRelPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput             

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

..

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

boby

 

 

 

 

d

 

 

 

 

cygdrive

 

 

  Step 6: Continue the same process until the queue “tmpQueueRelPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

cygdrive

 

 

 

Step 7: Continue the same process until the queue “tmpQueueRelPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

 

 

 

d

 

 

 

 

cygdrive

 

 

 

Step 8: Once the queue “tmpQueueRelPath” exhausts, pop the content of the stack “tmpStackCurrPath” and push it to the stack “tmpStackOutput”.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

cygdrive

 

temp.txt

  Step 9: Repeat the process till the stack “tmpStackCurrPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

cygdrive

 

temp.txt

 

 

Step 10: Repeat the process till the stack “tmpStackCurrPath” exhausts.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cygdrive

 

 

 

 

d

 

 

 

 

temp.txt

 

Step 11: Once the stack “tmpStackCurrPath” is empty, take the content into absolute return path string.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

temp.txt

 

pcAbsPath = “/cygdrive/

 

Step 12: Repeat the process till stack “tmpStackOutput” is empty.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput               

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

temp.txt

 

pcAbsPath = “/cygdrive/d/

 

Step 13: Repeat the process till stack “tmpStackOutput” is empty.

                  tmpQueueRelPath              tmpStackCurrPath                   tmpStackOutput                    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

pcAbsPath = “/cygdrive/d/ temp.txt  

 

Summary

    We can think of lots of different methods for the above implementation. Feedback about this method will be greatly appreciated. Contact me at bobypt@gmail.com. 

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Boby Thomas P
Software Developer (Senior) DWS
Australia Australia

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Comments and Discussions

 
GeneralBug on PC - case sensitive PinmemberR o n n y9-Jun-07 3:48 
GeneralVery useful, but this algorithm is not always correct PinmemberShura Kotov29-Aug-06 20:53 
Generalsimple and functional PinmemberBila128-Aug-06 6:04 
GeneralThese functions exist in the windows shell and CRT PinmemberEric Gur18-Apr-06 10:55 
GeneralRe: These functions exist in the windows shell and CRT PinmemberBoby Thomas P18-Apr-06 21:53 
GeneralRe: These functions exist in the windows shell and CRT PinmemberEric Gur19-Apr-06 9:46 
QuestionAnother way PinmemberDavidCrow18-Apr-06 3:17 
GeneralNice logic Pinmemberprasad_v_k17-Apr-06 19:05 
GeneralRe: Nice logic PinmemberAmr Shahin5-Nov-06 21:03 
GeneralCode is not DBCS-aware PinsitebuilderMichael Dunn16-Apr-06 6:35 
Generalnice logic Pinmemberismail2315-Apr-06 21:45 
GeneralNotes PinmemberYoSilver15-Apr-06 10:33 
GeneralRe: Notes PinmemberBobyThomasP15-Apr-06 21:21 
thanks for the info. Will that work for linux ?? Anyway let me check.
I will check that.Smile | :)
 
Regards,
Boby
Generalgreat idea Pinmembergomas_1115-Apr-06 7:57