writing user function + not valid stream resource

cal

I am trying to make my code more efficient by creating a function to hold code that is repeated.

Old code (that works):

// this block appends the file with a single line of all the responses in the same order as the variable list (hopefully)		
		if($fp = fopen("reg.txt", "ab")) { // open the file appending in binary mode
			$j = 0; // counter set to zero
			foreach($_POST as $i => $val) { // foreach loop in form elements, each arry element name is set to $i, its value set to $val
				if( $j != count($_POST) - 1 ) // if we are not on the last element of the arry,
					fwrite($fp, $val."\t"); // write data with a tab
				else // if we ~are~ on the last element of the array,
					fwrite($fp, $val."\n"); // write data with a new line
				$j = $j + 1; // increment the counter
			}
			fclose($fp); // close the file

So I took out the bit that would be repeated and created this function:

function filewrite() {
	$j = 0; // counter for the foreach command, since foreach uses the array's native element names and not a number
			foreach($_POST as $i => $val) { // foreach loop in form elements, each array element name is set to $i, its value set to $val
				if( $j != count($_POST) - 1 ) // if we are not on the last element of the array,
					fwrite($fp, $i."\t"); // write data with a tab
				else // if we ~are~ on the last element of the array,
					fwrite($fp, $i."\n"); // write data with a new line
				$j = $j + 1; // increment the counter
			}
			fclose($fp); // close the file
}

Using this function gets this error: Warning: fwrite(): supplied argument is not a valid stream resource in ... line 19
Line 19: fwrite($fp, $i."\t"); // write data with a tab

When I look at solutions to this error message, all I get is the chmod setting is wrong. However, the old code worked with the present security setup. So what is really causing the error?

Thank you.

bradgrafelman

When posting PHP code, please use the board's [noparse]

..

[/noparse] bbcode tags as they make your code much easier to read and analyze.

Your problem has nothing to do with permissions issues and everything to do with undefined variables. In your function, $fp is undefined (and an undefined variable is, of course, not a valid stream resource).

Perhaps you meant to pass in $fp as a function parameter?

cal

I defined the variable. You are right. I need to pass $fp as a function parameter.

Thanks for getting me straight and for alerting me to the bbcode tags. I am all for making code easier to read!