Quick question on reading files in C

I don't know how to tell the computer to stop reading when the file is done. I was looking around online and one example had

Code:

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while(!feof(file))

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but don't that gave me a seg fault. Can anyone clarify this for me?

actually it reads into some space and returns weird numbers.

There's an FAQ entry

What the FAQ says

looking at this example confused me, could you explain why they did an fgets on buffer?

Code:

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while (fgets(buf, sizeof(buf), fp) != NULL)

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Because that's how you read things in. fgets is, I mean.

no i understand fgets but I don't understand why they pass in buf and sizeOf(buf). I don't get how that has anything to do with the file size of junk1.txt

It doesn't. It's not supposed to.

The idea, TaiL, is that:

"If the system is already at end of file when you call fgets, then the contents of the array are unchanged and a null pointer is returned." (GNU)

There could be a flaw in this method too if the EOF occurs before/without a newline.

so is this basically the concept?

char nullChkr[50];

while (fgets(nullChkr, 50, fp) != NULL)

nullChkr would get overwritten with a NULL when fp is done. thus kicking me out of the loop?

No, nullchkr wouldn't get overwritten -- fgets would return NULL and not change the value of the argument.

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Originally Posted by TaiL

nullChkr would get overwritten with a NULL when fp is done. thus kicking me out of the loop?

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Don't think about it as "nullChkr", though (it's a filled character buffer) -- if you just want to find the last byte of a file , use a ++loop with fseek. If you decide to do that then take data from the file, you need to rewind the filestream.

No. nullChkr will not be overwritten with NULL. nullChkr gets filled with bytes read from the file. If there is an EOF detected, you may not get the full 49 (+1 for the nul) bytes asked for... The string, however much of it, in nullChkr will be terminated by a nul in any case. fgets() returns the pointer to the string, or NULL - in which case nullChkr's contents would not be touched.