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pr

Problem with my c# application :
I have file 202.txt I need to extract ip address from it and save the all ip in another file ip.txt

problem that occur :

Object reference not set to an instance of an object.

in line : string str = "http://" + currLine.Substring(currLine.IndexOf("2"), (currLine.IndexOf(":")) - 2) + "/";

i guess the problem is the null in the end of file how i can solve the problem.

StreamReader srFile = new StreamReader("e:\\202.txt");
            StreamWriter ip = new StreamWriter("e:\\ip.txt");
            
            string currLine = srFile.ReadLine();
            
            int f = currLine.IndexOf("2");
            int l = currLine.IndexOf(":");
            while (currLine != null)
            {
                if(currLine.Contains(".")){
                currLine = srFile.ReadLine();
                
               string str = "http://" + currLine.Substring(currLine.IndexOf("2"), (currLine.IndexOf(":")) - 2) + "/";
               ip.WriteLine(str);
                }
            }

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Dirk Haest

Can you attach the file also, so we can test the code...
When the error happens, what is the value of currLine ?

I also think that you'll never leave the loop if the line does not contain "." because in that case you don't read any other line ... --> infinite loop

StreamReader srFile = new StreamReader("e:\\202.txt");
            StreamWriter ip = new StreamWriter("e:\\ip.txt");
            
            string currLine = srFile.ReadLine();
            
            int f = currLine.IndexOf("2");
            int l = currLine.IndexOf(":");
            while (currLine != null)
            {
                if(currLine.Contains("."))
                {                                
                   string str = "http://" + currLine.Substring(currLine.IndexOf("2"), (currLine.IndexOf(":")) - 2) + "/";
                    ip.WriteLine(str);
                }
                currLine = srFile.ReadLine();
            }

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YUYU

ASKER

i use notepad++ to open it . 202.txt

magadesign_sviluppo

hi,
try:

StreamReader srFile = new StreamReader("e:\\202.txt");
            StreamWriter ip = new StreamWriter("e:\\ip.txt");
            
            string currLine = srFile.ReadLine();
            
            while (currLine != null)
            {
                  int f = currLine.IndexOf("2");
                int l = currLine.IndexOf(":");
                if(f!=-1 && l!=-1){
                
               string str = "http://" + currLine.Substring(f, (l) - 2) + "/";
               ip.WriteLine(str);
                }
                currLine = srFile.ReadLine();
            }

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hope it helps,
but this is valid if all ip starts with "2"
if not:

StreamReader srFile = new StreamReader("e:\\202.txt");
            StreamWriter ip = new StreamWriter("e:\\ip.txt");
            
            string currLine = srFile.ReadLine();
            
            while (currLine != null)
            {
                  int f = 2;//index of first letter of ip
                int l = currLine.IndexOf(":");
                if(l!=-1){
                
               string str = "http://" + currLine.Substring(f, (l) - 2) + "/";
               ip.WriteLine(str);
                }
                currLine = srFile.ReadLine();
            }

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this would help

Pratima

StreamReader srFile = new StreamReader("e:\\202.txt");
StreamWriter ip = new StreamWriter("e:\\ip.txt");

string currLine = srFile.ReadLine();

int f = currLine.IndexOf("2");
int l = currLine.IndexOf(":");
while (currLine != null)
{
if(currLine.Contains(".")){

string str = "http://" + currLine.Substring(currLine.IndexOf("2"), (currLine.IndexOf(":")) - 2) + "/";
ip.WriteLine(str);
currLine = srFile.ReadLine();
}
}

YUYU

ASKER

magadesign_sviluppo :

sorry your code not work .

Dirk Haest

I don't get any error with the file you provided ...

StreamReader srFile = new StreamReader("e:\\202.txt");
            StreamWriter ip = new StreamWriter("e:\\ip.txt");
            
            string currLine = srFile.ReadLine();
            
            int f = currLine.IndexOf("2");
            int l = currLine.IndexOf(":");
            while (currLine != null)
            {
                if(currLine.Contains("."))
                {                                
                   string str = "http://" + currLine.Substring(currLine.IndexOf("2"), (currLine.IndexOf(":")) - 2) + "/";
                    ip.WriteLine(str);
                }
                currLine = srFile.ReadLine();
            }

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YUYU

ASKER

pratima_mcs code work without problem but doesn't write to ip.txt file .

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magadesign_sviluppo

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