CLI PHP Script - Show escaped/formatting characters - php

Question

So this question applies for lots of languages, so don't be thrown off by the fact I'm using PHP in the terminal. An answer for say Python or Perl would probably also give what I need to know.
So I'm reading a text file, and I want to know what special characters are contained on every line. So for example, if the text file is this:
hello
world
I want the script to output "hello\nworld". My root problem is that I'm trying to write a PHP script which involves reading from a text file but I want it to ignore the blank lines but no matter what I try it still reads in the blank lines. I think it's because I'm not putting in the right match for the line so I'm trying to figure out how a blank line exists and I'm unsure if it's "\n" or "\t\t" etc.

Answer 1

Just do ordinary str_replace() like this:
$text = str_replace( array("\n","\r"), array('\n', '\r'), $text);

Answer 2

My solution, certainly more tedious, will remove blank lines, CLI PHP Script requires Shebang at the head:
#!/usr/bin/php
<?php
//
// main test:
//
$xarr = file("MyFilename.txt");
$n = count($xarr);
$strret = "";
for($i = 0; $i < $n; $i++)
{
//
// ignore blank lines:
//
if(! preg_match("/^$/", $xarr[$i]))
{
if($i > 0)
{
$strret .= "\\n";
}
$strret .= rtrim($xarr[$i]);
}
}
//
echo $strret . "\n";
?>
With a text file:
# cat MyFilename.txt
hello
world
It puts:
hello\nworld

Answer 3

I'll assume that by "special character", you mean only \n, \t, and \r.
Text file:
hello
world
foo
bar!
baz_
PHP:
$fp = fopen('textfile.txt', 'r');
while (!feof($fp)) {
$c = fgetc($fp);
if ($c == "\n") $c = '\n';
else if ($c == "\t") $c = '\t';
else if ($c == "\r") $c = '\r';
echo $c;
}
What the script above will basically do, is read each character of the file, and replace any occurrences of \t, \r, or \n that it finds. This eliminates the necessity to check for double-ups of characters.