Searching for a word in the text and highlighting it

Question

I am trying to write a php script that takes a text as an input, goes through the whole text (for example it can be a very long essay), and search for the word user inputs in the form.

It should print out the whole text with the highlighted word user was searching for, wherever it was found.

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title>Search for a word in text</title>
</head>

<body>

    <form method="post" action="index.php">
        <input type="text" name="text" placeholder="Insert the text you want to search in...">
        <input type="text" name="find_x" placeholder="Insert the word you want to find...">
        <input type="submit" value="Search">
    </form>

    <?php

        // this just prints out a line used to devide input area from a result
        $line = "<br>" . str_repeat("___", 40) . "<br></br>";
        echo $line;

        if ( isset($_POST["text"]) and !empty($_POST["text"]) and 
             isset($_POST["find_x"]) and !empty($_POST["find_x"]) ) 
        {
            $text = $_POST["text"];
            $find_x = $_POST["find_x"];

            // transforms inputs to lowercase so the word is found even if written in uppercase  
            $text_lc = strtolower($text);
            $find_x_lc = strtolower($find_x);

            // find length of searched word
            $length_of_x = strlen($find_x_lc);

            // variable for offsetting
            $offset = 0;

            // prints out all starting positions of a searched word
            while ( $position_in_text = strpos($text_lc, $find_x_lc, $offset) ) 
            {
                echo "The string <b><u>$find_x</u></b> is found in your text and it is at position $position_in_text" . "<br>";
                $offset = $position_in_text + $length_of_x;
            }


            // here I want to print the whole text, and wherever the searched word appears in the text it should be highlighted (bold or underlined). I don't know how to do that!?

        }

    ?>

</body>

You missed the comment where I say: " bellow is just something that should explain what I am trying to do, I know that this code will not work like this". — Nedzad Ganic, Dec 31 '16 at 01:30
I am trying to print the whole text and in that text every instance of searched word should be highlighted. The parse error is not the issue. That part of code would just print: ( - 1) + 6 — Nedzad Ganic, Dec 31 '16 at 01:32
You just went over the code to fast and didn't saw what I was actually trying to do — Nedzad Ganic, Dec 31 '16 at 01:33
I've reopened it, thanks for making it right. You'd be amazed as to what people will post as answers, based on what's posted. — Funk Forty Niner, Dec 31 '16 at 01:46
Thank you. I understand and from now on will take more care when asking a question — Nedzad Ganic, Dec 31 '16 at 01:49

score 0 · Accepted Answer · edited Dec 31 '16 at 03:12

Instead of using strpos you could use stripos, this way you can keep the case sensitivity as well. Also note the while( false !== stripos() ) may not even run if the search text is at position 0, meaning that it's at the start of the string, thus the need to check if stripos/strpos will return false or not ( false if no match had been found ).

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title>Search for a word in text</title>
</head>

<body>

    <form method="post" action="index.php">
        <input type="text" name="text" placeholder="Insert the text you want to search in...">
        <input type="text" name="find_x" placeholder="Insert the word you want to find...">
        <input type="submit" value="Search">
    </form>

    <?php

        // this just prints out a line used to devide input area from a result
        $line = "<br>" . str_repeat("___", 40) . "<br></br>";
        echo $line;

        if ( isset($_POST["text"]) and !empty($_POST["text"]) and
             isset($_POST["find_x"]) and !empty($_POST["find_x"]) )
        {
            $text = $_POST["text"];
            $find_x = $_POST["find_x"];

            // transforms inputs to lowercase so the word is found even if written in uppercase
            //~ $text_lc = strtolower($text);
            //~ $find_x_lc = strtolower($find_x);

            // find length of searched word
            //~ $length_of_x = strlen($find_x_lc);
            $length_of_x = strlen($find_x);

            // variable for offsetting
            $offset = 0;

            // prints out all starting positions of a searched word
            while ( false !== ( $position_in_text = stripos($text, $find_x, $offset) ) )
            {
                $found_string = substr( $text, $position_in_text, $length_of_x );

                echo "The string <b><u>", htmlspecialchars( $found_string ), "</u></b> is found in your text and it is at position $position_in_text" . "<br>";
                // maybe even sanitizing or escaping some of the texts? XSS here
                //~ $replacement = sprintf( '<strong>%s</strong>', htmlspecialchars( $found_string ) );
                $replacement = sprintf( '<strong>%s</strong>', $found_string );
                $text = substr_replace( $text, $replacement, $position_in_text, $length_of_x );
                $offset = $position_in_text + strlen( $replacement );
            }

            echo $line, $text;             
        }

    ?>

</body>

Text:
hello world HELLO again and good night heLLo

Search string:
hello

Expected Result should look like:
<strong>hello</strong> world <strong>HELLO</strong> again and good night <strong>heLLo</strong>

Great solution, it does exactly what I was trying to accomplish. Thank you. — Nedzad Ganic, Dec 31 '16 at 03:10
Your welcome, but please make sure you sanitize and escape all the strings which will be displayed in the browser, because as it stands it's open to XSS attacks. — Mujnoi Gyula Tamas, Dec 31 '16 at 03:13

Searching for a word in the text and highlighting it

1 Answers1