Matlab Read And Write Problems
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From: Adam on 12 Jun 2010 17:34 Hi, I have a function that rewrites a file using fopen and fclose. The problem is nothing is actually replaced until I open that file. For example: Let's say I'm rewrite the contents in testfile.m. Then I try to use testfile.m right after the rewrite my progrem doesn't work. However if I open testfile.m the contents have been rewritten. In fact, if I close testfile.m and try to use it, now it will work. Basicly after re-writing, I have to manually open and close the file for it to work. What am I doing wrong? I tried adding a pause, in case the computer had to catch up, but that doesn't work. Thanks a lot, Adam
From: us on 12 Jun 2010 17:40 "Adam " <abc5(a)ubc.ca> wrote in message <hv0ugd$nmn$1(a)fred.mathworks.com>... > Hi, > > I have a function that rewrites a file using fopen and fclose. The problem is nothing is actually replaced until I open that file. > > For example: > Let's say I'm rewrite the contents in testfile.m. Then I try to use testfile.m right after the rewrite my progrem doesn't work. However if I open testfile.m the contents have been rewritten. In fact, if I close testfile.m and try to use it, now it will work. Basicly after re-writing, I have to manually open and close the file for it to work. What am I doing wrong? I tried adding a pause, in case the computer had to catch up, but that doesn't work. > > Thanks a lot, > Adam which os do you use(?)... do you work on a local hd(?)... us
From: dpb on 12 Jun 2010 17:39 Adam wrote: > Hi, > > I have a function that rewrites a file using fopen and fclose. The > problem is nothing is actually replaced until I open that file. I think you mean until you close the file, really. The i/o subsystem is probably buffering the contents of the write until either the buffer is full or until it's closed at which time the buffer has to be flushed. > For example: .... > What am I doing wrong? I tried adding a pause, in case the computer had > to catch up, but that doesn't work. .... No, that's not likely the problem; see above. If the above doesn't make sense, repost w/ the sequence of the actual code but if you're expecting to not close the file after the update and then reuse the new contents, change your expectations... :) --
From: Adam on 12 Jun 2010 18:00 dpb <none(a)non.net> wrote in message <hv0uv7$p4a$1(a)news.eternal-september.org>... > Adam wrote: > > Hi, > > > > I have a function that rewrites a file using fopen and fclose. The > > problem is nothing is actually replaced until I open that file. > > I think you mean until you close the file, really. The i/o subsystem is > probably buffering the contents of the write until either the buffer is > full or until it's closed at which time the buffer has to be flushed. > > > For example: > ... > > > What am I doing wrong? I tried adding a pause, in case the computer had > > to catch up, but that doesn't work. > ... > No, that's not likely the problem; see above. > > If the above doesn't make sense, repost w/ the sequence of the actual > code but if you're expecting to not close the file after the update and > then reuse the new contents, change your expectations... :) > I'm using fclose(fid). And am I working on a local HD, I don't think that is the problem though. Even if I wait 30 seconds then try to use the file, it still won't work. What I am doing is 'importing" a .m file with a bunch of equations written very simply (could also be a .txt). Then I'm rewriting those equations into another function lets call it feval. When the user hits my start button, it runs an algorithm that uses feval a lot (which is why it is easier to just rewrite the feval function upon import). The problem is, when I import the file, nothing seems to change to feval. Hitting start will run whatever was there before. If I open (manually) I can see that it's been replaced, then if I hit start and it run the new code. Here is my file import function: fid2=fopen('feval.m','w'); %Stuff that is always there. fprintf(fid2,'%s \n','function [t,p]=testfun(x)'); fprintf(fid2,'%s \n','%Test1'); ...Print my new imported functions here... fprintf(fid2,'%s \n','end') fclose(fid2)
From: Adam on 12 Jun 2010 18:07
Sorry I missed your last post. The buffer sounds like it's likely the problem. I'll look into to how to flush it. |