generate qr code using c# Lesson 1: Exploring Common Server Controls in visual C#.net

Writer QRCode in visual C#.net Lesson 1: Exploring Common Server Controls

Although comparing strings is useful for sorting them or for detecting equality, sometimes you need just to examine the characters within a string . The String type offers several properties and methods to help you do this, including Length, Chars (an indexer in C#), GetEnumerator, ToCharArray, Contains, IndexOf, LastIndexOf, IndexOfAny, and LastIndexOfAny . In reality, a System.Char represents a single 16-bit Unicode code value that doesn t necessarily equate to an abstract Unicode character . For example, some abstract Unicode characters are a combination of two code values . When combined, the U+0625 (the Arabic letter Alef with Hamza below) and U+0650 (the Arabic Kasra) characters form a single abstract character or text element . In addition, some Unicode text elements require more than a 16-bit value to represent them . These text elements are represented using two 16-bit code values . The first code value is called the high surrogate, and the second code value is called the low surrogate . High surrogates have a value between U+D800 and U+DBFF, and low surrogates have a value between U+DC00 and U+DFFF . The use of surrogates allows Unicode to express more than a million different characters . Surrogates are rarely used in the United States and Europe but are more commonly used in East Asia . To properly work with text elements, you should use the System.Globalization.StringInfo type . The easiest way to use this type is to construct

At Microsoft s request, Wintellect has produced the Power Collections library to bring some of the C++ Standard Template Library s collection classes to the CLR programmer . This library is a set of collection classes that anyone can download and use free of charge . See http://Wintellect.com for details . These collection classes are generic themselves and make extensive use of generics . Table 12-1 shows a list of some of the collection classes you ll find in the Power Collections library .

Begin by starting Office Groove 2007 as you would any other 2007 Microsoft Office system suite application; the Launchbar appears on your desktop to help you create and manage your activities in Office Groove 2007 (see Figure 11-1).

Listing 9-34. Querying for a point too far back in time select empno, ename, deptno, msal from e AS OF TIMESTAMP to_timestamp('01-OCT-2004 10:53:42.000'); * ERROR at line 2: ORA-01466: unable to read data - table definition has changed Of course, the timestamps to be used in Listing 9-32 depend on the timing of your experiments. Choose appropriate timestamps if you want to test these statements yourself. If you executed the steps of Listing 9-31 with some decent time intervals (as suggested), you have enough appropriate candidate values to play with. The Oracle error message at the bottom of Listing 9-32 indicates that this query is trying to go back too far in time. In this case, table E didn t even exist. Data definition changes (ALTER TABLE E ...) may also prohibit flashback queries, as suggested by the error message text.

USE tempdb; GO CREATE TABLE t1 ( ID INT IDENTITY(1,1) PRIMARY KEY, NAME VARCHAR(64), GEOM GEOMETRY );

cn.Open();

The message, including the asterisk (*), reveals the problem here. The Oracle DBMS cannot figure out which DEPTNO column we are referring to. Both tables mentioned in the FROM clause have a DEPTNO column, and that s why we get an error message.