C#

int position=0;<br />
		char[] KeywordsCanStartWith  = {'_','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q',<br />
										   'r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I',<br />
										   'J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'} ;<br />
		char[] KeywordsEndBeforeApears = {' ','\t','(',')',',','.',';','\n','[',']','{','}','+','-','*','/',':',<br />
											 '=','<','>','|','\\','&','%','?','$','!','"','#','\'','@','^'} ;<br />
		bool LogVar;<br />
		//give blue color to all keywords(=words)<br />
		void giveColorToKeywordsInRTB(object sender, System.EventArgs e)<br />
		{<br />
			position=0;<br />
			KeywordStartsHere=-1; caretPos=richTextBox1.SelectionStart;	<br />
			LogVar=true;<br />
			LockWindowUpdate(richTextBox1.Handle);<br />
			richTextBox1.Select(0, richTextBox1.Text.Length);<br />
			richTextBox1.SelectionColor = Color.Black ;<br />
			while(LogVar)<br />
			{<br />
				KeywordStartsHere = richTextBox1.Text.IndexOfAny(KeywordsCanStartWith , position);<br />
				if(position<0)<br />
					break ;				<br />
				if(position==KeywordStartsHere)<br />
				{<br />
					position = richTextBox1.Text.IndexOfAny(KeywordsEndBeforeApears, position) ;<br />
					if(position==-1)<br />
						position=richTextBox1.Text.Length-1 ;<br />
					else<br />
						position--;<br />
					richTextBox1.Select(KeywordStartsHere, position-KeywordStartsHere+1);<br />
					richTextBox1.SelectionColor = Color.Blue ;<br />
				}<br />
			}<br />
				if(++position > richTextBox1.Text.Length-1)<br />
					LogVar=false;<br />
			}<br />
		}