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Alyce
Feb 4, 2012
=Creating a Name for Temporary Files= //[[user:Alyce]] // [[toc|flat]] ---- =Writing Temporary Files= Security measures in Windows prevents programs from writing files to all areas. Use the Windows API to retrieve the user's temporary directory and to create a temporary filename that is unlikely to be used by another application. =GetTempPathA= To insure that your program can successfully write a temporary file on the user's computer, use the function [[GetTempPathA]] to retrieve the path to a directory where temporary files should be created. =GetTempFileNameA= The **GetTempFileNameA** function allows you to create a unique temporary filename. The name is in this format: TemporaryPath$ + ThreeCharPrefix + HexadecimalString$ + ".TMP" An example that uses GetTempPathA for the temporary path and "xyz" for the prefix might look like this: C:\DOCUME~1\MYNAME~1\LOCALS~1\Temp\xyzDA7.tmp The function looks like this: [[code format="lb"]] calldll #kernel32, "GetTempFileNameA",_ TempPath$ as ptr,_ 'directory for temp file prefix$ as ptr,_ 'desired prefix for temp filename unique as ulong,_ '0=file created,nonzero=you must create file TempFile$ as ptr,_ 'string buffer to hold qualified path and filename result as ulong 'nonzero=success [[code]] The TempPath$ string can contain any directory. It can be the DefaultDir$, for instance. Best practice dictates that you use the [[GetTempPathA]] function to retrieve the user's temporary directory. The prefix$ argument should be one to three characters long. Some examples: abc rgf aa b xyz zy The "unique" argument tells the function whether to create the file, or to simply return the filename. If it is 0, the function creates the file, thus assuring its existence. If the value for unique is nonzero, the programmer must create the file himself. TempFile$ should be a string buffer of blank spaces that will receive the temporary filename returned by the function. This is a fully qualified path and filename, as in the example above. Best practice dictates that you should delete your temporary file when your program closes, or when it is no longer needed. Use the **KILL** statement to do this. =Demo= This demo program retrieves the path to the temporary directory. It created a prefix of "xyz". It creates a string variable full of blank spaces that will hold the fully qualified path and filename to the temporary file when the function returns. The demo does not write anything to the file, nor does it delete the file on exit. You will do both of these things when you include the code in your program. [[code format="lb"]] TempPath$=GetTempPath$() prefix$="xyz" 'up to 3 characters for desired prefix TempFile$ = space$(256)+chr$(0) calldll #kernel32, "GetTempFileNameA",_ TempPath$ as ptr,_ 'directory for temp file prefix$ as ptr,_ 'desired prefix for temp filename 0 as ulong,_ '0=file created,nonzero=you must create file TempFile$ as ptr,_ 'string buffer to hold qualified path and filename result as ulong 'nonzero=success 'TempFile$ holds complete path and filename info print TempFile$ end Function GetTempPath$() CallDLL #kernel32, "GetTempPathA",_ 0 as long,_ _NULL as long,_ length as long buf$ = space$(length) CallDLL #kernel32, "GetTempPathA",_ length as long,_ buf$ as ptr,_ ret as long GetTempPath$ = buf$ End Function [[code]] ---- See also: [[GetTempPathA]] ---- [[toc|flat]]