(.NET Core C#) Extract data:image/png;base64 from HTML

Demonstrates how to extract base64 image data from HTMl and save to files.

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Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
Chilkat.BinData bd = new Chilkat.BinData();
Chilkat.StringBuilder sbFilename = new Chilkat.StringBuilder();
int index = 1;

bool success = sb.LoadFile("qa_data/html/oresp body.txt","utf-8");
// Assume success.
Debug.WriteLine("length = " + Convert.ToString(sb.Length));

bool mayHaveMore = true;
while (mayHaveMore == true) {

    // Get the base64 between the 1st occurrence "data:image/png;base64," and "'"
    string sBase64 = sb.GetBetween("data:image/png;base64,","'");

    // If nothing is found, then we'll exit the loop because there are no more.
    mayHaveMore = sb.LastMethodSuccess;

    if (sb.LastMethodSuccess == true) {
        // Found something.
        // Load into bd and save.
        success = bd.LoadEncoded(sBase64,"base64");

        sbFilename.SetString("qa_output/png_");
        sbFilename.AppendInt(index);
        sbFilename.Append(".png");

        bd.WriteFile(sbFilename.GetAsString());

        // Replace "data:image/png;base64" with "data:image-png;base64" so the next iteration finds the next occurrence.
        sb.ReplaceFirst("data:image/png;base64","data:image-png;base64");
    }

    index = index + 1;
}

// Restore our replacements..
int count = sb.Replace("data:image-png;base64","data:image/png;base64");

Debug.WriteLine("All done.");