Question

It would be preferable if the code is able to create a new file.
eg: If my file originally is:
fsyfugiuhknklmoiuiuutyughvhjbiuhi
jhiubuguygfvtdrcrsresetgfcyuhijoj

and the new file desired contains a new line char after every 3rd position:
fsy
fug
iuh
knk
…

what should be the code.?

Answer 1

void InsertACharacterNoStringAfterEveryNCharactersInAHugeTextFileUsingCSharp(
    string inputPath, string outputPath, int blockSize, string separator)
{
    using (var input = File.OpenText(inputPath))
    using (var output = File.CreateText(outputPath))
    {
        var buffer = new char[blockSize];
        int readCount;
        while ((readCount = input.ReadBlock(buffer, 0, buffer.Length)) > 0)
        {
            output.Write(buffer, 0, readCount);
            if (readCount == buffer.Length)
                output.Write(separator);
        }
    }
}

// usage:
InsertACharacterNoStringAfterEveryNCharactersInAHugeTextFileUsingCSharp(
    inputPath, outputPath, 3, Environment.NewLine);