quick fclose question

This is a discussion on quick fclose question within the C Programming forums, part of the General Programming Boards category; what can cause fclose to fail? and another question: why would rename fail? thanks...

  1. #1
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    quick fclose question

    what can cause fclose to fail? and another question: why would rename fail?

    thanks
    Last edited by ihatejava; 10-09-2002 at 11:14 PM.

  2. #2
    Registered User Azuth's Avatar
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    what can cause fclose to fail?
    The file's been closed already? The file was deleted before you closed it?

    Are you just curious? Or do you have a related issue? If so, post some code.

    (Use Code tags)
    Demonographic rhinology is not the only possible outcome, but why take the chance

  3. #3
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    Code:
    if (fclose(f1) == EOF || fclose(f2) == EOF || fclose(g1) == EOF || fclose(g2) == EOF)
    		{
    			printf("Error! Could not close all files.\n");
    			return (0);
    		}
    
    		renameFailed = rename(file1, gFile1);
    		printf("rename1: %d\n", renameFailed); \\ test
    		renameFailed = rename(file2, gFile2);
    		printf("rename2: %d\n", renameFailed); \\ test
    		renameFailed = rename(gFile1, file1);
    		printf("rename3: %d\n", renameFailed); \\ test
    		renameFailed = rename(gFile2, file2);
    		printf("rename4: %d\n", renameFailed); \\ test
    		if (renameFailed != 0)
    		{
    			printf("Internal file processing error\n");
    			break;
    		}
    Excuse the crappy code OK this is the part that's giving me trouble. This line is executed printf("Error! Could not close all files.\n"), then it returns. f1, f2, g1, g2 should all be open, so why does fclose fail? The print statements are just tests but renameFailed is always -1. I suppose that rename would fail if fclose failed earlier, but why do they all fclose/rename fail?

  4. #4
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    all i know is fclose returns 0 upon successfull close.
    "with a gun barrel between your teeth, you speak only in vowels."
    - tyler durden

  5. #5
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    all i know is fclose returns 0 upon successfull close.
    yes it does. maybe i'll try testing for 0 instead of EOF...

  6. #6
    End Of Line Hammer's Avatar
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    Originally posted by ihatejava
    yes it does. maybe i'll try testing for 0 instead of EOF...
    Read the fclose() man page:
    0 = Success
    non-zero = an error occurred. errno is set to indicate the error.
    So to test fclose() to see if it failed:
    >>if (fclose(fp) != 0) printf ("close failed\n");


    And again for the rename() function:
    The rename() function returns zero if the operation succeeds, a non-zero value if it fails. When an error has occurred, errno contains a value that indicates the type of error that has been detected.
    Just use perror() to find out what went wrong.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

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