How to calculate total line number of a text file

How to calculate total line number of a text file?
I have a text file. I want to get the total line number of it. Could somebody know which function should I use? Or I should write the counting code for each line?

Code:

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int c;
while((c=fgetc(f))!=EOF)
  if(c=='\n')
    ++num_lines;

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Use ifstream and its getline function.
For each successful getline function call increment a variable.

Write code like below..

Code:

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        CStdioFile sampleFile;
        sampleFile.Open( "\\...myfile.txt", CFile::modeRead );

        long length = 0;
        CString temp("");
        while( sampleFile.ReadString( temp ) )
        {
                length++;
        }

// length contains your line count..

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Thanks,
dwurity