vb.net print barcode Part I CLR Basics in .NET

Embed qr-codes in .NET Part I CLR Basics

public sealed class Program { public static void Main() { CompanyB.BetterPhone phone = new CompanyB.BetterPhone(); phone.Dial(); } }

MethodInfo #1 MethodInfo #2

// if color is valid if ( COLOR_MIN <= color && color <= COLOR_MAX ) { // do something ... } else { // else color is invalid // screen not written to - safely ignore command }

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$params = array (':customer_id' => $customerId, ':name' => $name, ':email' => $email, ':password' => $hashed_password, ':day_phone' => $dayPhone, ':eve_phone' => $evePhone, ':mob_phone' => $mobPhone); // Prepare the statement with PDO-specific functionality $result = DatabaseHandler::Prepare($sql); // Execute the query return DatabaseHandler::Execute($result, $params); } public static function DecryptCreditCard($encryptedCreditCard) { $secure_card = new SecureCard(); $secure_card->LoadEncryptedDataAndDecrypt($encryptedCreditCard); $credit_card = array(); $credit_card['card_holder'] = $secure_card->CardHolder; $credit_card['card_number'] = $secure_card->CardNumber; $credit_card['issue_date'] = $secure_card->IssueDate; $credit_card['expiry_date'] = $secure_card->ExpiryDate; $credit_card['issue_number'] = $secure_card->IssueNumber; $credit_card['card_type'] = $secure_card->CardType; $credit_card['card_number_x'] = $secure_card->CardNumberX; return $credit_card; } public static function GetPlainCreditCard() { $customer_data = self::Get(); if (!(empty ($customer_data['credit_card']))) return self::DecryptCreditCard($customer_data['credit_card']); else return array('card_holder' => '', 'card_number' => '', 'issue_date' => '', 'expiry_date' => '', 'issue_number' => '', 'card_type' => '', 'card_number_x' => ''); } public static function UpdateCreditCardDetails($plainCreditCard, $customerId = null) { if (is_null($customerId)) $customerId = self::GetCurrentCustomerId();

Figure 8-25. The JCal Pro presentation is very attractive and works across the spectrum of web browsers.

Here you don t have to flip-flop if and else clauses; the expressions in the last two code fragments are logically equivalent. To apply DeMorgan s Theorems to the logical operator and or the logical operator or and a pair of operands, you negate each of the operands, switch the ands and ors, and negate the entire expression. Table 19-1 summarizes the possible transformations under DeMorgan s Theorems:

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By default, the Windows Firewall exception for Remote Assistance is enabled only on private networks.

Read committed snapshot is a row versioning based implementation of the read committed isolation level that can be used on a per-database basis . The database option READ_ COMMITTED_SNAPSHOT controls which version of read committed is used . As soon as you set this database option to ON, all sessions working at the read committed level (default) will actually be working at the read committed snapshot level . This is a database global behavioral change that you get just by setting the database option to ON, making it very easy to use because no code changes are required . The read committed snapshot isolation level differs from the snapshot isolation level in two ways . The first difference is that readers get the latest consistent version of data that was available when the statement started, as opposed to when the transaction started . The second difference is that this isolation level does not detect update conflicts, just like read committed . This isolation level is especially useful for applications that you migrate from platforms that support obtaining earlier consistent versions of data, such as when an application migrates from Oracle to SQL Server . Readers don t need to wait when data has been modified but not committed, and you don t sacrifice the consistency of your reads as you do with the read uncommitted isolation level . To look at the read committed snapshot isolation level, first turn on the database option in the testdb database:

This code generates the following output:

Error handling has taken a major leap forward with the introduction of the TRY/CATCH construct . When you use TRY/CATCH your error-handling code is more structured, elegant, and traps all errors except for the most severe ones . It also provides a lot of useful information via the error-related functions . When you are using TRY/CATCH, and an error happens in an explicit transaction, your session can end up in one of three different transaction states: no transaction open, open and committable, or open and uncommittable (failed) . Remember that the failed state allows you to keep a transaction open, holding all locks, while you re investigating data . You then must roll back the transaction before making any change . I hope that future versions of SQL Server will add more error-handling features, such as throwing system errors, rethrowing errors, and autonomous transactions, to name a few .