The SplFileObject::key() is an inbuilt function of the Standard PHP Library (SPL) in PHP that is used to get the key (line number) of the current line pointed to by the SplFileObject.
Syntax
public SplFileObject::key(): int
Parameter
This function does not have any parameters.
Return Value
The SplFileObject::key() function returns the current line number in the form of an integer. The first line starts from 0 and the second line number is 1.
Program 1: The following program demonstrates the SplFileObject::key() function. Before running this program you must save this file (“output.txt”) in your current working directory.
PHP
<?php $file = new SplFileObject("./output.txt", "r"); while (!$file->eof()) { // Get the current line $line = $file->current(); $lineNumber = $file->key(); echo "Line $lineNumber: $line" . PHP_EOL; // Advance to the next line $file->next(); } ?> |
output.txt:
This is a text Simple example Another example here
Output:
Line 0: This is a text Line 1: Simple example Line 2: Another example here
Program 2: The following program demonstrates the SplFileObject::key() function. Before running this program you must save this file (“output.txt”) in your current working directory.
PHP
<?php $file = new SplFileObject("./output.txt", "r"); while (!$file->eof()) { $lineNumber = $file->key(); // Get the current line content $line = $file->current(); if ($lineNumber % 2 === 0) { // Check if the line number is even echo "Line $lineNumber: $line" . PHP_EOL; } $file->next(); } ?> |
output.txt:
Line 1 Line 2 Line 3 Line 4 Line 5
Output:
Line 0: Line 1 Line 2: Line 3 Line 4: Line 5
Reference: https://www.php.net/manual/en/splfileobject.key.php
