[SCIP] how can I output my best solution using SCIPgetBestSol() to a file?

[Leon Eifler]

Hi Melvin and Naga,

the SCIPprintSol function expects a normal FILE*, as Naga already 
pointed out. A SCIP_FILE* is either a FILE* or a gzFile, depending on if 
you compiled with ZLIB or without.

Therefore, you need to use a normal FILE* if you want to write a 
solution to a file.

Cheers,
Leon

On 14.09.20 09:14, Naga Venkata Chaitanya Gudapati - 
nagavenkata.gudapati at studio.unibo.it wrote:
> Looks like I jumped the gun a little and just saw your full email and the attempt at trying to print the solution to a file. I am not sure about the inner workings of SCIP_FILE *  but a normal C-style FILE * seems to be working okay.
>
> ________________________________________
> From: Scip <scip-bounces at zib.de> on behalf of Naga Venkata Chaitanya Gudapati - nagavenkata.gudapati at studio.unibo.it <nagavenkata.gudapati at studio.unibo.it>
> Sent: Monday, September 14, 2020 7:56 AM
> To: Melvin Shih; scip at zib.de
> Subject: Re: [SCIP] how can I output my best solution using SCIPgetBestSol() to a file?
>
> Hi!
>
> If I understood your question correctly,
>
> You need to use
>
> SCIP_RETCODE SCIPprintSol(SCIP * scip,  SCIP_SOL * sol,  FILE * file, SCIP_Bool printzeros )    ;
>
> In c++, if you just want to print the solution to the console with all the 0 variable printed too, you can use:
>   SCIP_SOL* sol = nullptr;
>   sol = SCIPgetBestSol(scip);
>   SCIP_CALL(SCIPprintSol (scip, sol, nullptr, 1));
>
> If you want to write to a file with 0s,
> SCIP_SOL* sol = nullptr;
> sol = SCIPgetBestSol(scip);
> FILE *fp;
> fp = fopen("MYSOL.TXT", "w+");
> SCIP_CALL(SCIPprintSol (scip, sol, fp, 1));
> fclose(fp);
>
> I also have a Minimum Working Example if you need. I hope this is what you are looking for. I hope other SCIP members will chime in if I am wrong.
>
> Regards,
> Naga
>
>
>
> ________________________________________
> From: Scip <scip-bounces at zib.de> on behalf of Melvin Shih <melvinshih at gmail.com>
> Sent: Sunday, September 13, 2020 8:09 PM
> To: scip at zib.de
> Subject: [SCIP] how can I output my best solution using SCIPgetBestSol() to     a file?
>
> Dear SCIP members,
>
> I have tried functions of fstream and SCIP_FILE to open a file for SCIPgetBestSol(), and they do not work.
> Is there any example to define a file for  SCIPgetBestSol() or is there another way to do so using C++?
>
> Sincerely,
>
> Melvin shih
>
>
> Here are my codes:
> .............
> // fstream file;
> // file.open("Reader.txt", ios::out | ios::trunc);       //not work
>
> SCIP_FILE* schedulingfile;
> char filename[255];
> (void)SCIPsnprintf(filename, 255, "Sintex.txt");
> schedulingfile = SCIPfopen(filename, "r");
> if (schedulingfile == NULL)
> {
> SCIPerrorMessage("cannot open file <%s> for reading\n", filename);
> SCIPprintSysError(filename);
> return SCIP_NOFILE;
> }
> if (SCIPgetNSols(scip) > 0)
> {
> SCIPinfoMessage(scip, NULL, "\nSolution:\n");
> SCIP_CALL(SCIPprintSol(scip, SCIPgetBestSol(scip), schedulingfile, FALSE));   //SCIP_FILE is not accepted
> }
> SCIPfclose(schedulingfile);
> ..........
>
>
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