PHP正则表达式在字符串后回显字符

Question

I have a large .txt file, within the .txt file, it contains the numbers 712 and other characters. example (712iu3 89234) or (712jnksuiosd). The characters after 712 will change, they may have spaces. I have a php script that reads the file line by line. I am trying to echo all characters after 712 If there are spaces I'd like to remove the spaces. I only need the first 20 characters excluding the spaces. So far I've tried

$file = new SplFileObject("1.txt");

// Loop until we reach the end of the file.
while (!$file->eof()) {
// Echo one line from the file.
echo $file->fgets();
}

// Unset the file to call __destruct(), closing the file handle.
$file = null;

Answer 1

try using the code below

<?php 
$file = new SplFileObject("test.txt");

// Loop until we reach the end of the file.
while (!$file->eof()) {
    $newString = str_replace(' ', '', $file->fgets());
if (strpos($newString, '712') !== false) {
    $strWith712 = substr($newString, 0, 20);
    $post = strripos($strWith712, '712');
    $str =  substr ($strWith712, $post );
    echo $str;

}

}

$file = null;
?>

this replaces the white spaces and then searches for the string with the number '712' if a string is found then the letters after the number are printed
the strripos function is used to check the postiton of the string in a sentence from the last.