c# Substring doesn't find string

Question

I have this paragraph inside my lotHtmlOriginal.Text

waters71 </strong></p>
<p><strong>websitesss.com/sblogin/login.shtml/</strong><br />
<strong>1234213:123123</strong><br />
<strong>213123:12312</strong><br />
<strong>4213:196028</strong><br />
<strong>32131:43423</strong><br />
<strong>4444444:96980507</strong></p>
<p><strong>htt

I issue is that when I make the second part of substring , the code fails because substring is not able to find it, but when I change it to certain things, it works.

It does not work when I change it too...

htt
tron
p

This is my code

String St = lotHTMLOriginal.Text; ;
String firstPart = "blogin/login.shtml/</strong>";
String lastPart = "</p>";
int pFrom = St.IndexOf(firstPart) + firstPart.Length;
int pTo = St.IndexOf(lastPart);

String result = St.Substring(pFrom, pTo - pFrom);
lotHTML.Text = result;

And just in case it's not clear, I'm trying to get everything between blogin/login.shtml/ and 

I'm trying to get everything between blogin/login.shtml/ and  — TeethPain
– TeethPain, Commented May 21, 2015 at 4:40
Because IndexOf() only find the first , while what you want is the last ? — shole
– shole, Commented May 21, 2015 at 4:40
@shole does it not find the first after the firstPart? — TeethPain
– TeethPain, Commented May 21, 2015 at 4:42
If you know the patterns you're matching against, why not use a Regular Expression? — Dai
– Dai, Commented May 21, 2015 at 4:42

Alexei Levenkov · Accepted Answer · 2015-05-21 04:42:49Z

2

It looks like you want to find particular string starting from previously found position like string.IndexOf:

int pTo = St.IndexOf(lastPart, pFrom);

Side note: if you need a lot of HTML processing it may be easier to use HTML parser (like HtmlAgilityPack) instead of using string matching or regular expressions, but for simple one-off code substring is ok.

answered May 21, 2015 at 4:42

Alexei Levenkov

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Comments

Glenn Ferrie · Accepted Answer · 2015-05-21 04:51:35Z

I believe this will fix the bug in your code. I've added a new variable to the mix. Let me know if this makes sense / helps.

    String St = lotHTMLOriginal.Text; ;
    String firstPart = "blogin/login.shtml/</strong>";
    String lastPart = "</p>";
    int pFrom = St.IndexOf(firstPart) + firstPart.Length;

    // these three lines changed
    string St_temp = St.Substring(pFrom);
    int pTo = St_temp.IndexOf(lastPart);
    String result = St.Substring(pFrom, pTo);

    lotHTML.Text = result;

What I ultimately did was to trim the characters before firstPart in St to simplify the code somewhat. It limits the arithmetic you need to do to get the result you are looking for.

// this is the result
<br />
<strong>1234213:123123</strong><br />
<strong>213123:12312</strong><br />
<strong>4213:196028</strong><br />
<strong>32131:43423</strong><br />
<strong>4444444:96980507</strong>

Hossein Narimani Rad · Accepted Answer · 2015-05-21 04:54:10Z

0

Using int pTo = St.IndexOf(lastPart); you will get the index of the first , but you are looking for the last one so I think you should use

int pTo = St.LastIndexOf(lastPart);

OUTPUT:

 1234213:123123 213123:12312 4213:196028 32131:43423 4444444:96980507

edited May 21, 2015 at 4:54

answered May 21, 2015 at 4:48

Hossein Narimani Rad

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Comments

Michael · Accepted Answer · 2015-05-21 05:01:59Z

0

This code will find the first "" after the beginning of the firstPart.

String lastPart = "</p>";
int pFrom = St.IndexOf(firstPart) + firstPart.Length;
int pTo = 0;
while(pTo - pFrom < 0)
{
    pTo = St.IndexOf(lastPart);
}

edited May 21, 2015 at 5:01

answered May 21, 2015 at 4:45

Michael

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