get URL from a string. Pls, help me!

For ex:
I have a string as below:
string s = "There is some thing in http://www.abc.com/def/ghi/z.jpg and some else from http://abc123.com/78u/adf/1.jpg .......";
I want write a function return the results:
1. http://www.abc.com/def/ghi/z.jpg
2. http://abc123.com/78u/adf/1.jpg
function may be like: public string[] getURLFromString(string _s) {}

Can anybody help me?
Thanks.

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