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C Syntax (Toggle Plain Text)
C Syntax (Toggle Plain Text)
Why those functions does not return error value but terminate whole program? How can I safely tell if file is opened in C and close it???
If variable of type 'FILE*' is passed to my function I need to know the state of the file and be able to close.
Any idea?
Last edited by edek : 4 Days Ago at 8:58 am.
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Posting Whiz
what did you expect it to do?
you're trying to do the close and tell function on a NULL pointer.
now think about that for a minute, and you should have your answer.
.
you're trying to do the close and tell function on a NULL pointer.
now think about that for a minute, and you should have your answer.
.
Last edited by jephthah : 3 Days Ago at 12:52 pm.
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> Terminates with: 'No source available for "fclose@@GLIBC_2.1() " '
You get these in debug builds because the code for fclose uses assert() to validate the input parameters.
If you were in a debugger at the time, you'd know exactly where to start looking.
In this case, fclose() is likely to begin with
Release builds have no assert() statements, so it would just return whatever the spec says fclose() should return if passed NULL.
You get these in debug builds because the code for fclose uses assert() to validate the input parameters.
If you were in a debugger at the time, you'd know exactly where to start looking.
In this case, fclose() is likely to begin with
assert( fp != NULL );
Release builds have no assert() statements, so it would just return whatever the spec says fclose() should return if passed NULL.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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Posting Whiz
well, i just learned something.
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Originally Posted by Salem 
Release builds have no assert() statements, so it would just return whatever the spec says fclose() should return if passed NULL.
Actually, it terminates in release build. It should return error value, though. It might be some internal inconsistency of the implementation of C lib I am using (glibc2.1).
Last edited by edek : 3 Days Ago at 8:29 am.
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> Actually, it terminates in release build.
Is that because it detected NULL and cleanly exited, or dereferenced NULL and bombed?
Is that because it detected NULL and cleanly exited, or dereferenced NULL and bombed?
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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Originally Posted by Salem
Is that because it detected NULL and cleanly exited, or dereferenced NULL and bombed?
It seems to cleanly exit with the value -1. It does not return value to indicate error, it exits the whole application with value -1.
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I've found something like (http://www.stanford.edu/~thathoo/cur...io.h/code.html line 204):
What does
C Syntax (Toggle Plain Text)
'function is a possible cancellation point' mean?? Does it mean that it can cancel whole application on error? Last edited by edek : 2 Days Ago at 1:21 pm.
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