PHP：If / Else Statement：条件条款

I have a script - where a user can view data from a text file, choose a line number, and then that line number (and corresponding text from the text file) will appear on another page.

The script from the 2nd page, copied below, works. But I want to add in an if/else statement (or something else is ok), which states something like: IF the line number exists (and it can be accessed/displayed) - here it is. ELSE, that number doesn't exist try again. //webpage 1 Show:

//webpage 2 showtest.php
<?php
$searchfor = $_GET['keyword2'];

$lines = file('users.txt');
$l_count = count($lines);
for($x = 0; $x< $l_count; $x++)
{
}

echo $lines[$searchfor];
?> 

WHAT I AM AIMING FOR

$lines = file('users.txt');
$l_count = count($lines);
for($x = 0; $x< $l_count; $x++)
{
}
if(....................){

echo "Match found:<br />";
echo $lines[$searchfor];}

else{(...................)
echo "This is not a valid term";
}

if(array_key_exists($searchedfor,$lines)){...}else{...}

Should work for you

Using the file function stores everything in an array and you could therefore just search through the array using the in_array function. By adding the FILE_IGNORE_NEW_LINES a newline at the end of each array element. Experiment with adding this.

<?php
$file = file('users.txt',FILE_IGNORE_NEW_LINES);
if(in_array('string',$file))
{
   echo 'string exists';
}
?>