如何从HTML元素字符串获取子字符串？

Question

I use asp.net project in server side.

I have this string: <img src="../../SpatialData/sometext/813.jpg" style="width:190px">

at some point I need to extruct src from string:

../../SpatialData/sometext/813.jpg  

How can I get substring using c#?

Answer 1

You can use some regex to solve that...

var test = "<img src=\"../../SpatialData/sometext/813.jpg\" style=\"width:190px\">";

var pattern = @"<img src=""([^\""]*)";

var result = Regex.Match(test, pattern).Groups[1].Value;

Console.WriteLine(result);

The issue is... if you're performing that function against any html document with multiple image tags, it's not going to work, to get them all...

test = "<img src=\"../../SpatialData/sometext/813.jpg\" style=\"width:190px\"><img src=\"../../SpatialData/sometext/814.jpg\" style=\"width:190px\">";

var matches = Regex.Matches(test, pattern)
                   .Cast<Match>()
                   .Select(x=>x.Groups[1].Value);

foreach (var m in matches)
{
    Console.WriteLine(m);
}

As someone has already stated, HTML agility pack is an option worth looking into, the solution I've provided above is very rigid, if the attributes on the image tag were to be reordered differently, those elements would not be included in the results