CODEWITHSUNDEEP
php
Richard
Richard

Reputation:

Printing special characters in php

I have a php variable which contains data from an IO stream (say, a file I've just read). This string contains a number of special characters such as \n and \t and so forth. I need to be able to print all of these characters to screen so that I can examine the string visually. I'm presuming there's some way of escaping them, but for the life of me I can't figure out how.

Upvotes: 5

Views: 1396

Answers (3)

Luke Cousins
Luke Cousins

Reputation: 2156

I think this is a very old question but none of the answers are very helpful. We use this function for examining strings like this, so hopefully it can help someone else out:

function convert_non_visual_ascii_chars_to_representation($string) {
    $non_vis_chars = [
        0 => 'NUL',
        1 => 'SOH',
        2 => 'STX',
        3 => 'ETX',
        4 => 'EOT',
        5 => 'ENQ',
        6 => 'ACK',
        7 => 'BEL',
        8 => 'BS',
        9 => 'TAB',
        10 => 'LF',
        11 => 'VT',
        12 => 'FF',
        13 => 'CR',
        14 => 'SO',
        15 => 'SI',
        16 => 'DLE',
        17 => 'DC1',
        18 => 'DC2',
        19 => 'DC3',
        20 => 'DC4',
        21 => 'NAK',
        22 => 'SYN',
        23 => 'ETB',
        24 => 'CAN',
        25 => 'EM',
        26 => 'SUB',
        27 => 'ESC',
        28 => 'FS',
        29 => 'GS',
        30 => 'RS',
        31 => 'US',
    ];

    // Convert the string
    $new_string = '';
    $length = strlen($string);
    for ($i = 0; $i < $length; $i++) {
        $char_code = ord($string[$i]);
        if (isset($non_vis_chars[$char_code])) {
            $new_string = $new_string . '[' . $non_vis_chars[$char_code] . '/' . $char_code . ']';
        } else {
            $new_string = $new_string . $string[$i];
        }
    }

    return $new_string;
}

Upvotes: 0

usoban
usoban

Reputation: 5478

Well interesting question. I haven't been able to find anything in Google about escaping newline char.

I guess you could try using nl2br, which would convert your newlines to <br />, but that isn't quite useful, since you won't know when you have an actual break tag or newline char.

So, to get past this, you I recommend two options. If you only want to examine the string, use var_dump() or var_export()

The following code gives gives the output 'text \\n':

$var = 'text \n';

var_export($var);

Or, if you want to work further with it, you can use a piece of code like that, but let's be honest, this is quite messy...

$var = 'text \n';

$search = array('\n', '\r', '\r\n');
$replace = array('[n]', '[r]', '[r][n]');

echo str_replace($search, $replace, $var);

This would output text [n]

Upvotes: 0

aaz
aaz

Reputation: 5196

addcslashes("test\n", "\0..\37\177..\377")

Upvotes: 2

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