What regular expression needs to be used to extract a particular value from an HTML tag?

Question

What regular expression can be used to extract the value of src attribute in the iframe tag?

regex should not be used for parsing something as complex and *wierd* as html document. use library meant to be used for that kind of task. — dantuch, Aug 25 '13 at 18:49
possible duplicate of [RegEx match open tags except XHTML self-contained tags](http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags) — , Aug 26 '13 at 02:27

score 4 · Answer 1 · answered Aug 26 '13 at 02:23

If you really are using Java (not JavaScript) and you only have the iframe, you can try the regular expression:

(?<=src=")[^"]*(?<!")

e.g.:

private static final Pattern REGEX_PATTERN = 
        Pattern.compile("(?<=src=\")[^\"]*(?<!\")");

public static void main(String[] args) {
    String input = "<iframe name=\"I1\" id=\"I1\" marginwidth=\"1\" marginheight=\"1\" height=\"430px\" width=\"100%\" border=\"0\" frameborder=\"0\" scrolling=\"no\" src=\"report.htm?view=country=us\">";

    System.out.println(
        REGEX_PATTERN.matcher(input).matches()
    );  // prints "false"

    Matcher matcher = REGEX_PATTERN.matcher(input);
    while (matcher.find()) {
        System.out.println(matcher.group());
    }
}

Output:

report.htm?view=country=us

score 0 · Answer 2 · answered Aug 25 '13 at 19:09

0

I would say look into dom parsing. from there it would be extremely similar to the javascript answer. Dom parser will turn the html into a document from there you can do:

iframe = document.getElementById("I1"); src = iframe.getAttribute("src");

answered Aug 25 '13 at 19:09

user2716032

1
1

score 0 · Answer 3 · answered Aug 25 '13 at 19:16

Regex is little bit costlier do not use it until you have other simple solution, in java try this

String src="<iframe name='I1' id='I1' marginwidth='1' marginheight='1'" + 
" height='430px' width='100%' border='0' frameborder='0' scrolling='no'" +
" src='report.htm?view=country=us'>";

int position1 = src.indexOf("src") + 5;
System.out.println(position1);

int position2 = src.indexOf("\'", position1);
System.out.println(position2);

System.out.println(src.substring(position1, position2));

Output:

134
160
report.htm?view=country=us

score -1 · Answer 4 · answered Aug 25 '13 at 18:36

-1

In case you meant javascript instead of java:

var iframe = document.getElementById("I1");
var src = iframe.getAttribute("src");
alert(src); //outputs the value of the src attribute

answered Aug 25 '13 at 18:36

Jeroen Ingelbrecht

808
5
11

No, I'm pretty sure he wants to use Java. – Josh M Aug 25 '13 at 18:37
He stated he is using Java. – Josh M Aug 25 '13 at 18:40

score -1 · Answer 5 · edited May 23 '17 at 10:31

-1

 src="(.*?)"

The regular expression will match src="report.htm?view=country=us", but you will find only the part between the " in the first (and only) submatch.

When you only want to match src-attributes when they are in an iframe, do this:

<iframe.*?src="(.*?)".*?>

but there are certain corner-cases where this could fail due to the inherently non-regular nature of HTML. See the top answer to RegEx match open tags except XHTML self-contained tags for an amusing rant about this problem.

edited May 23 '17 at 10:31

Community

1
1

answered Aug 25 '13 at 18:39

Philipp

67,764
9
118
153

@djechlin I did point out that it can't parse any HTML, but it will parse the HTML in the question. I also think that your criticism would be more constructive when you would offer a better solution instead of just complaining. – Philipp Aug 25 '13 at 20:01
Comments that point out problems in solutions are constructive. They tell the reader "this won't work." The better solution is to use an HTML parser. – djechlin Aug 25 '13 at 20:10

What regular expression needs to be used to extract a particular value from an HTML tag?

5 Answers5