[RESOLVED] Delete a line in a text file

[coderunner]

Hello forum readers,

I want to delete a special line in a flat file but can't solve it.
I searched the internet but didn't find a solution, always get the error $id is undefined.
I hope someone can help me

flat file -> $id|$name|$address|$city

00001|name 1|address 1|city 1
00002|name 2|address 2|city 2
00003|name 3|address 3|city 3
00004|name 4|address 4|city 4
00005|name 5|address 5|city 5
00006|name 6|address 6|city 6
00007|name 7|address 7|city 7
00008|name 8|address 8|city 8
00009|name 9|address 9|city 9

This is my code to read the flat file. The delete code is missing

<?php
$do = isset($_REQUEST['do']) ? trim($_REQUEST['do']) : "";
$self = $_SERVER['PHP_SELF'];
$data_file = "textfile.txt";

switch ($do) 
	{
    case "";

		$file_handle = fopen($data_file, "rb");
			while (!feof($file_handle) ) 
			{
				$lines = file($data_file); 
				$line_of_text = fgets($file_handle);
				$row = explode('|', $line_of_text);

					$id = $row[0];
					$name = $row[1];
					$address = $row[2];
					$city = $row[3];
			
					echo '<div style="width:400px;">
						<form method="post" action="'.$self.'" enctype="multipart/form-data" >
							<input type="hidden" name="do" value="delete_data">
							
							<input type="hidden" name="id" value="'.$id.'" />'.$name.'
							<input type="submit" name="delete" value="Delete" />
						</form>
						</div>'; 
									

			}
				fclose($file_handle);
        break;


	case "delete_data";

		//Here code to delete selected line
	
		break;
	}
?>

Eg. I want to delete line with id=00003 and line with id=00007. What is de code to do this with using $id ? (without just entering a number like 3 or 7 in the code)
I hope somebody can help me write the case "delete_data" code.

Thanks already for those who can help me

Best regards

[NogDog]

I often find it useful to read the entire file into an array via the file() function, delete the desired array element, then implode() the array into a string and overwrite the file with that string via file_put_contents().

[coderunner]

Hello NogDog,

Thanks for your reply.

Is it possible to give me the code itself, I'm a beginner and that way I can learn of it and try to understand it.

Thanks in advance

Kind regards

[NogDog]

The basics:

$file = '/path/to/some/file.txt';
$lines = file($file); // add some error-checking here to make sure it worked
$filtered = '';
foreach($lines as $line) {
   if(<you want to keep this line>) {
      $filtered .= $line;
   }
}
file_put_contents($file, $filtered); 

(You could replace that foreach() loop with a call to array_filter(), then implode() that result, but this way is probably easier to comprehend for now. )

[coderunner]

Hello again NogDog,

Where do I have to put the $id (=first row of the line of flat file) of the form in this code so it only deletes the line when I click on the delete button?

Sorry for all myquestions but as I said before I'm a totally beginner.

Thanks for helping me.

Best regards

[coderunner]

Anybody who can give me a working code for deleting a line that works for my code?
That way I can examine the code and learn of it.
Hope someone can help me here.

Thanks in advance.

Kind regards

[coderunner]

Found it ... finally ...

Thanks for your help NogDog

Regards