feof error Leetonia Ohio

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feof error Leetonia, Ohio

There are three lines here. Linked 5 C reading binary files 0 How to read numbers from file and calculate the mean? 2 How does C handle EOF? 1 How do I loop through each line Only then feof returns non-zero. If you get an error, it sets the error flag; if you reach the end of the file during a read, it sets the EOF flag.

It is always necessary to check the return value of a read (either an fread(), or an fscanf(), or an fgetc()) before calling feof(). Search: Reference feof function feof int feof ( FILE * stream );Check end-of-file indicator Checks whether the end-of-File indicator associated with stream is set, returning a value different from Built-in Function: msg = ferror (fid) Built-in Function: [msg, err] = ferror (fid) Built-in Function: [dots] = ferror (fid, "clear") Query the error status of the stream specified by file descriptor The environment is not part of your program, and not under your control.

Even worse, consider the case where a read error occurs. feof() does not return true until after a read on the stream encounters the end of file. C stdio, scanf: for (int a, b, c; scanf("%d %d %d", &a, &b, &c) == 3; ) { consume(a, b, c); } The result we must use is the return value In it, you'll get: The week's top questions and answers Important community announcements Questions that need answers see an example newsletter By subscribing, you agree to the privacy policy and terms

This page has been accessed 9,468 times. Example // read binary data, checking for eof or error int main(void) { int a; FILE *fp; fp = fopen("binaryints.dat", "rb"); // read single ints at a time, stopping on EOF Your read must test for an error.Fix 1A:C/CPP/C++ Code Example: while (!feof(st)) { if (fgets(buf, 20, st) != NULL) { // process your buffer puts(buf); } } fclose(st); Fix 1B:C/CPP/C++ Code To workaround this, see below example: Example #1 Handling timeouts with feof() functionsafe_feof($fp,&$start

Maybe even possible with sizeof(line) == 1. –chux Mar 26 '15 at 21:21 add a comment| up vote 4 down vote Great answer, I just noticed the same thing because I Developing web applications for long lifespan (20+ years) New tech, old clothes How do investigators always know the logged flight time of the pilots? See also: fclear, fopen. This is however not a common loop condition - usually you want to test for something else (such as "can I read more").

In some function is the loop where you are reading and handling this data. As with all things concurrent, questions about the "current state" don't make sense: There is no concept of "simultaneity" across concurrent events. This may be due to a bad link, or the item being moved or deleted. The point here is that we can only know how many bytes were written after the write operation.

What can I do?0Comparing syntax to feof0counting rows in excel with feof() in c1Why the last iteration repeats?-1Reading from file and exiting loop using feof() Hot Network Questions Is intelligence the Example
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While using this site, you agree to have read and accepted our terms of use, cookie and privacy policy. RelatedThings to Avoid in C/C++ -- gets() , Part 1Things to Avoid in C/C++ -- fflush(stdin), Part 2Things to Avoid in C/C++ -- scanf, Part 5Things to Avoid in C/C++ -- In the case of the end of the file being reached, if characters were read, it returns buffer. However, you have to use it carefully in conjunction with fgets().

So, it's wrong in that scenario, but if you want to have a loop that gracefully ends at the EOF, this is a nice way to do it: #include #include The conclusion is that there simply is no property like "I have data", since you cannot act meaningfully in response to any possible answer. (The situation is slightly better with buffered The result is that you are erroneously executing code that assumes that it is accessing data that was read successfully, when in fact this never happened. The idea was to provide a guiding template to illustrate how to read data from a file appropriately and safely, though obviously it isn't necessarily correct for all use cases.

If the value didn't signal an error, and the value returned by fscanf isn't EOF, meaning neither ferror nor feof would return a value other than 0, there is badly formatted So, in summary, although I cannot state with certainty that there is never a situation in which it may be semantically correct to write "while(!feof(f))" (although there must be another check And possibly slap the author (unless the author is your boss in which case discretion is advised.) share|improve this answer edited Sep 17 '15 at 15:59 answered Mar 25 '11 at Fopen( argv[ 1 ], "r" ) : stdin; count = 0; /* WARNING: this is a bug */ while( !feof( in )) { /* This is WRONG! */ (void) fgetc( in

Of course there are exceptions, but that is a matter of implementation detail and the desired and available functionalities. Using C++ iostreams, it goes like this: std::string input = " 123 "; // example std::istringstream iss(input); int value; if (iss >> value >> std::ws && iss.get() == EOF) { consume(value); feof($file)) { echo fgets($file). "
"; } fclose($file); ?> The output of the code above will be: Hello, this is a test file. I can't really think of any case I've needed it, usually I'm interested in "could I read what I wanted" with all that implies of error handling –Erik Mar 25 '11

For instance: while (fgets(line, sizeof(line), file)) { /* note that fgets don't strip the terminating \n, checking its presence allow to handle lines longer that sizeof(line), not showed here */ ... Note that I used a scanset in the last bit to ignore an invalid line entirely, which only works with a conforming C99 library. Parameters handle The file pointer must be valid, and must point to a file successfully opened by fopen() or fsockopen() (and not yet closed by fclose()). What is the most expensive item I could buy with £50?

In all cases where while(!feof(p)) is used, there must be at least a check inside the loop for ferror(), or at the very least the while condition should be replaced with c o m ¶10 years ago you can avoid the infinite loop and filling the error logs
by an simple if statement
Here is the example

Let me make this more precise: Suppose you want to ask, "do you have more data". Looking for Kratom Merchant Account Need Echeck or ACH account ACH for Pharma, Nutra, Adult, LI and Tech as low as 1.95% ServerHat.com | *70% OFF* | SSD Disk [$0.59 cPanel It is much more of a detail than we often care about. Return Value feof() and ferror() return non-zero (true) if the file has reached EOF or there has been an error, respectively.

Built-in Function: freport () Print a list of which files have been opened, and whether they are open for reading, writing, or both. To determine if there is more data to be read, use feof() instead of reading this item.

Another thing: better not rely on the "including socket timeout" part of The purpose of feof() is NOT to check if the next read will reach the end of file. The second input "clear" is optional.

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Consequently feof() is simply useless.
Before write this note I want to submit this as a php bug but one php developer said that Built-in Function: status = feof (fid) Return 1 if an end-of-file condition has been encountered for the file specified by file descriptor fid and 0 otherwise. This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h For example: freport () -| number mode arch name -| ------ ---- ---- ---- -| 0 r ieee-le stdin -| 1 w ieee-le stdout -| 2 w ieee-le stderr -| 3

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/* feof example: byte counter */ #include int main () { FILE * pFile; int n = 0; pFile = fopen ("myfile.txt","rb"); if (pFile==NULL) perror ("Error opening file"); If supplied, the error state on the stream will be cleared. See also clearerrClear error indicators (function )ferrorCheck error indicator (function ) C++ Information Tutorials Reference Articles Forum Reference C library: (assert.h) (ctype.h) (errno.h) (fenv.h) (float.h) This way, you will correctly determine eof under both unix/linux and windows.