How to modify data in a certain line of a file in php

Modification method: 1. Use the "fopen($file,'r ')" statement to open the specified file in read-write mode; 2. Use the while() loop and fgets() function to control the number of lines; 3. When fgets() reads the specified row of data, use the fseek() and fwrite() functions to modify the data of this row.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

php modify a file Method for one line of data

• Open the specified file in reading and writing mode

• Use while() loop fgets() Function to control the number of lines

  fgets() function can read the file line by line, reading one line of data at a time

• When specifying the number of lines, use fseek() and The fwrite() function modifies the data in this row.

Implementation code:

<?php
$file = "test.txt";
$fp = fopen($file, &#39;r+&#39;);
if ($fp) {
	$i = 1;
	while (!feof($fp)) {
		//修改第二行数据
		if ($i == 2) {
			fseek($fp, 0, SEEK_CUR);
			fwrite($fp, &#39;HELLO&#39;);
			break;
		}
		fgets($fp);
		$i++;
	}
	fclose($fp);
}
?>

Original content of test.txt file:

Modified content:

Description:

feof() function checks whether the end of file (EOF) has been reached. Returns TRUE if an error occurs or the file pointer reaches the end of file (EOF), otherwise it returns FALSE.

fseek() function locates in the open file. This function moves the file pointer forward or backward from the current position to a new position, measured in bytes from the beginning of the file. The function returns 0 on success and -1 on failure. Note that moving to a position after the end of file (EOF) does not produce an error.

fwrite() function can write a string to a file.

Recommended learning: "PHP Video Tutorial"

The above is the detailed content of How to modify data in a certain line of a file in php. For more information, please follow other related articles on the PHP Chinese website!