confirm valid file identifier before flcose?

12 vues (au cours des 30 derniers jours)
CM le 1 Fév 2024
Réponse apportée : CM le 2 Fév 2024
I am using GUI callbacks to close a file. Sometimes the file is aready closed, and I get an invalid file identifier error. Is there a robust way to check if the file is still open before calling fclose? I have tried using fopen('all') but that does not always catch it.

Réponse acceptée

Les Beckham
Les Beckham le 1 Fév 2024
If you call fopen on the file identifier when the file is closed it will return empty (instead of returning the filename). So, you can do this:
if ~isempty(fopen(fid))

Plus de réponses (2)

Voss le 1 Fév 2024
% file already closed, do nothing

CM le 2 Fév 2024
Thanks Les and Voss. I have actually combined both techniques, with the try inside the if loop. I am not using multithreading, so I am not sure if it is possible for the fid to become invalid within the space of the fopen and the if statements, but I have been going round in circles on this for a while and want to make sure it is robust.


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