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  • How to prompt for input using an existing variable in the prompt.

    - by ldigas
    I'm trying to ask the user for a value of some variable, but at the same time, showing him the last value used (at the termination of the program, the values are saved to a file, and loaded at the start of the program). Something like this: Enter new radius value (R=12.6) : ... user enters 12.7 ... Enter new pi value (pi=3.14) : Enter new height value (h=30.0) : Usually I would write the first one with write statement, then read the new one (in Fortran, for example). In MATLAB however, I don't know how to write something out with input statement. Are there some other statements for getting input ?

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  • Margin adjustments when using ggplot's geom_tile()

    - by chris_dubois
    From the documentation for ggplot2's geom_tile() function, we have the following simple plot: > # Generate data > pp <- function (n,r=4) { + x <- seq(-r*pi, r*pi, len=n) + df <- expand.grid(x=x, y=x) + df$r <- sqrt(df$x^2 + df$y^2) + df$z <- cos(df$r^2)*exp(-df$r/6) + df + } > p <- ggplot(pp(20), aes(x=x,y=y)) > > p + geom_tile() How do I remove the margins that border the tile?

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  • Python: confused with classes, attributes and methods in OOP

    - by user1586038
    A. Am learning Python OOP now and confused with somethings in the code below. Question: 1. def init(self, radius=1): What does the argument/attribute "radius = 1" mean exactly? Why isn't it just called "radius"? The method area() has no argument/attribute "radius". Where does it get its "radius" from in the code? How does it know that the radius is 5? """ class Circle: pi = 3.141592 def __init__(self, radius=1): self.radius = radius def area(self): return self.radius * self.radius * Circle.pi def setRadius(self, radius): self.radius = radius def getRadius(self): return self.radius c = Circle() c.setRadius(5) """ B. Question: In the code below, why is the attribute/argument "name" missing in the brackets? Why was is not written like this: def init(self, name) and def getName(self, name)? """ class Methods: def init(self): self.name = 'Methods' def getName(self): return self.name """

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  • How to write a variable with input ?

    - by ldigas
    the title is somewhat vague, so let me explain I'm trying to ask the user for a value of some variable, but at the same time, showing him the last value used (at the termination of the program, the values are saved to a file, and loaded at the start of the program). Something like this: Enter new radius value (R=12.6) : ... user enters 12.7 ... Enter new pi value (pi=3.14) : Enter new height value (h=30.0) : Usually I would write the first one with write statement, then read the new one (in fortran, for example). In matlab however, I don't know how to write something out with input statement. Are there some other statements for getting input ? All your thoughts on the subject appreciated.

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  • What types of programming contest problems are there?

    - by Alex
    Basically, I want to make a great reference for use with programming contests that would have all of the algorithms that I can put together that I would need during a contest as well as sample useage for the code. I'm planning on making this into a sort of book that I could print off and take with me to competitions. I would like to do this rather than simply bringing other books (such as Algorithms books) because I think that I will learn a lot more by going over all of the algorithms myself as well as I would know exactly what I have in the book, making it more efficient to have and use. So, I've been doing research to determine what types of programming problems and algorithms are common on contests, and the only thing I can really find is this (which I have seen referenced a few times): Hal Burch conducted an analysis over spring break of 1999 and made an amazing discovery: there are only 16 types of programming contest problems! Furthermore, the top several comprise almost 80% of the problems seen at the IOI. Here they are: Dynamic Programming Greedy Complete Search Flood Fill Shortest Path Recursive Search Techniques Minimum Spanning Tree Knapsack Computational Geometry Network Flow Eulerian Path Two-Dimensional Convex Hull BigNums Heuristic Search Approximate Search Ad Hoc Problems The most challenging problems are Combination Problems which involve a loop (combinations, subsets, etc.) around one of the above algorithms - or even a loop of one algorithm with another inside it. These seem extraordinarily tricky to get right, even though conceptually they are ``obvious''. Now that's good and all, but that study was conducted in 1999, which was 13 years ago! One thing I know is that there are no BigNums problems any more (as Java has a BigInteger class, they have stopped making those problems). So, I'm wondering if anyone knows of any more recent studies of the types of problems that may be seen in a programming contest? Or what the most helpful algorithms on contests would be?

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  • Toorcon14

    - by danx
    Toorcon 2012 Information Security Conference San Diego, CA, http://www.toorcon.org/ Dan Anderson, October 2012 It's almost Halloween, and we all know what that means—yes, of course, it's time for another Toorcon Conference! Toorcon is an annual conference for people interested in computer security. This includes the whole range of hackers, computer hobbyists, professionals, security consultants, press, law enforcement, prosecutors, FBI, etc. We're at Toorcon 14—see earlier blogs for some of the previous Toorcon's I've attended (back to 2003). This year's "con" was held at the Westin on Broadway in downtown San Diego, California. The following are not necessarily my views—I'm just the messenger—although I could have misquoted or misparaphrased the speakers. Also, I only reviewed some of the talks, below, which I attended and interested me. MalAndroid—the Crux of Android Infections, Aditya K. Sood Programming Weird Machines with ELF Metadata, Rebecca "bx" Shapiro Privacy at the Handset: New FCC Rules?, Valkyrie Hacking Measured Boot and UEFI, Dan Griffin You Can't Buy Security: Building the Open Source InfoSec Program, Boris Sverdlik What Journalists Want: The Investigative Reporters' Perspective on Hacking, Dave Maas & Jason Leopold Accessibility and Security, Anna Shubina Stop Patching, for Stronger PCI Compliance, Adam Brand McAfee Secure & Trustmarks — a Hacker's Best Friend, Jay James & Shane MacDougall MalAndroid—the Crux of Android Infections Aditya K. Sood, IOActive, Michigan State PhD candidate Aditya talked about Android smartphone malware. There's a lot of old Android software out there—over 50% Gingerbread (2.3.x)—and most have unpatched vulnerabilities. Of 9 Android vulnerabilities, 8 have known exploits (such as the old Gingerbread Global Object Table exploit). Android protection includes sandboxing, security scanner, app permissions, and screened Android app market. The Android permission checker has fine-grain resource control, policy enforcement. Android static analysis also includes a static analysis app checker (bouncer), and a vulnerablity checker. What security problems does Android have? User-centric security, which depends on the user to grant permission and make smart decisions. But users don't care or think about malware (the're not aware, not paranoid). All they want is functionality, extensibility, mobility Android had no "proper" encryption before Android 3.0 No built-in protection against social engineering and web tricks Alternative Android app markets are unsafe. Simply visiting some markets can infect Android Aditya classified Android Malware types as: Type A—Apps. These interact with the Android app framework. For example, a fake Netflix app. Or Android Gold Dream (game), which uploads user files stealthy manner to a remote location. Type K—Kernel. Exploits underlying Linux libraries or kernel Type H—Hybrid. These use multiple layers (app framework, libraries, kernel). These are most commonly used by Android botnets, which are popular with Chinese botnet authors What are the threats from Android malware? These incude leak info (contacts), banking fraud, corporate network attacks, malware advertising, malware "Hackivism" (the promotion of social causes. For example, promiting specific leaders of the Tunisian or Iranian revolutions. Android malware is frequently "masquerated". That is, repackaged inside a legit app with malware. To avoid detection, the hidden malware is not unwrapped until runtime. The malware payload can be hidden in, for example, PNG files. Less common are Android bootkits—there's not many around. What they do is hijack the Android init framework—alteering system programs and daemons, then deletes itself. For example, the DKF Bootkit (China). Android App Problems: no code signing! all self-signed native code execution permission sandbox — all or none alternate market places no robust Android malware detection at network level delayed patch process Programming Weird Machines with ELF Metadata Rebecca "bx" Shapiro, Dartmouth College, NH https://github.com/bx/elf-bf-tools @bxsays on twitter Definitions. "ELF" is an executable file format used in linking and loading executables (on UNIX/Linux-class machines). "Weird machine" uses undocumented computation sources (I think of them as unintended virtual machines). Some examples of "weird machines" are those that: return to weird location, does SQL injection, corrupts the heap. Bx then talked about using ELF metadata as (an uintended) "weird machine". Some ELF background: A compiler takes source code and generates a ELF object file (hello.o). A static linker makes an ELF executable from the object file. A runtime linker and loader takes ELF executable and loads and relocates it in memory. The ELF file has symbols to relocate functions and variables. ELF has two relocation tables—one at link time and another one at loading time: .rela.dyn (link time) and .dynsym (dynamic table). GOT: Global Offset Table of addresses for dynamically-linked functions. PLT: Procedure Linkage Tables—works with GOT. The memory layout of a process (not the ELF file) is, in order: program (+ heap), dynamic libraries, libc, ld.so, stack (which includes the dynamic table loaded into memory) For ELF, the "weird machine" is found and exploited in the loader. ELF can be crafted for executing viruses, by tricking runtime into executing interpreted "code" in the ELF symbol table. One can inject parasitic "code" without modifying the actual ELF code portions. Think of the ELF symbol table as an "assembly language" interpreter. It has these elements: instructions: Add, move, jump if not 0 (jnz) Think of symbol table entries as "registers" symbol table value is "contents" immediate values are constants direct values are addresses (e.g., 0xdeadbeef) move instruction: is a relocation table entry add instruction: relocation table "addend" entry jnz instruction: takes multiple relocation table entries The ELF weird machine exploits the loader by relocating relocation table entries. The loader will go on forever until told to stop. It stores state on stack at "end" and uses IFUNC table entries (containing function pointer address). The ELF weird machine, called "Brainfu*k" (BF) has: 8 instructions: pointer inc, dec, inc indirect, dec indirect, jump forward, jump backward, print. Three registers - 3 registers Bx showed example BF source code that implemented a Turing machine printing "hello, world". More interesting was the next demo, where bx modified ping. Ping runs suid as root, but quickly drops privilege. BF modified the loader to disable the library function call dropping privilege, so it remained as root. Then BF modified the ping -t argument to execute the -t filename as root. It's best to show what this modified ping does with an example: $ whoami bx $ ping localhost -t backdoor.sh # executes backdoor $ whoami root $ The modified code increased from 285948 bytes to 290209 bytes. A BF tool compiles "executable" by modifying the symbol table in an existing ELF executable. The tool modifies .dynsym and .rela.dyn table, but not code or data. Privacy at the Handset: New FCC Rules? "Valkyrie" (Christie Dudley, Santa Clara Law JD candidate) Valkyrie talked about mobile handset privacy. Some background: Senator Franken (also a comedian) became alarmed about CarrierIQ, where the carriers track their customers. Franken asked the FCC to find out what obligations carriers think they have to protect privacy. The carriers' response was that they are doing just fine with self-regulation—no worries! Carriers need to collect data, such as missed calls, to maintain network quality. But carriers also sell data for marketing. Verizon sells customer data and enables this with a narrow privacy policy (only 1 month to opt out, with difficulties). The data sold is not individually identifiable and is aggregated. But Verizon recommends, as an aggregation workaround to "recollate" data to other databases to identify customers indirectly. The FCC has regulated telephone privacy since 1934 and mobile network privacy since 2007. Also, the carriers say mobile phone privacy is a FTC responsibility (not FCC). FTC is trying to improve mobile app privacy, but FTC has no authority over carrier / customer relationships. As a side note, Apple iPhones are unique as carriers have extra control over iPhones they don't have with other smartphones. As a result iPhones may be more regulated. Who are the consumer advocates? Everyone knows EFF, but EPIC (Electrnic Privacy Info Center), although more obsecure, is more relevant. What to do? Carriers must be accountable. Opt-in and opt-out at any time. Carriers need incentive to grant users control for those who want it, by holding them liable and responsible for breeches on their clock. Location information should be added current CPNI privacy protection, and require "Pen/trap" judicial order to obtain (and would still be a lower standard than 4th Amendment). Politics are on a pro-privacy swing now, with many senators and the Whitehouse. There will probably be new regulation soon, and enforcement will be a problem, but consumers will still have some benefit. Hacking Measured Boot and UEFI Dan Griffin, JWSecure, Inc., Seattle, @JWSdan Dan talked about hacking measured UEFI boot. First some terms: UEFI is a boot technology that is replacing BIOS (has whitelisting and blacklisting). UEFI protects devices against rootkits. TPM - hardware security device to store hashs and hardware-protected keys "secure boot" can control at firmware level what boot images can boot "measured boot" OS feature that tracks hashes (from BIOS, boot loader, krnel, early drivers). "remote attestation" allows remote validation and control based on policy on a remote attestation server. Microsoft pushing TPM (Windows 8 required), but Google is not. Intel TianoCore is the only open source for UEFI. Dan has Measured Boot Tool at http://mbt.codeplex.com/ with a demo where you can also view TPM data. TPM support already on enterprise-class machines. UEFI Weaknesses. UEFI toolkits are evolving rapidly, but UEFI has weaknesses: assume user is an ally trust TPM implicitly, and attached to computer hibernate file is unprotected (disk encryption protects against this) protection migrating from hardware to firmware delays in patching and whitelist updates will UEFI really be adopted by the mainstream (smartphone hardware support, bank support, apathetic consumer support) You Can't Buy Security: Building the Open Source InfoSec Program Boris Sverdlik, ISDPodcast.com co-host Boris talked about problems typical with current security audits. "IT Security" is an oxymoron—IT exists to enable buiness, uptime, utilization, reporting, but don't care about security—IT has conflict of interest. There's no Magic Bullet ("blinky box"), no one-size-fits-all solution (e.g., Intrusion Detection Systems (IDSs)). Regulations don't make you secure. The cloud is not secure (because of shared data and admin access). Defense and pen testing is not sexy. Auditors are not solution (security not a checklist)—what's needed is experience and adaptability—need soft skills. Step 1: First thing is to Google and learn the company end-to-end before you start. Get to know the management team (not IT team), meet as many people as you can. Don't use arbitrary values such as CISSP scores. Quantitive risk assessment is a myth (e.g. AV*EF-SLE). Learn different Business Units, legal/regulatory obligations, learn the business and where the money is made, verify company is protected from script kiddies (easy), learn sensitive information (IP, internal use only), and start with low-hanging fruit (customer service reps and social engineering). Step 2: Policies. Keep policies short and relevant. Generic SANS "security" boilerplate policies don't make sense and are not followed. Focus on acceptable use, data usage, communications, physical security. Step 3: Implementation: keep it simple stupid. Open source, although useful, is not free (implementation cost). Access controls with authentication & authorization for local and remote access. MS Windows has it, otherwise use OpenLDAP, OpenIAM, etc. Application security Everyone tries to reinvent the wheel—use existing static analysis tools. Review high-risk apps and major revisions. Don't run different risk level apps on same system. Assume host/client compromised and use app-level security control. Network security VLAN != segregated because there's too many workarounds. Use explicit firwall rules, active and passive network monitoring (snort is free), disallow end user access to production environment, have a proxy instead of direct Internet access. Also, SSL certificates are not good two-factor auth and SSL does not mean "safe." Operational Controls Have change, patch, asset, & vulnerability management (OSSI is free). For change management, always review code before pushing to production For logging, have centralized security logging for business-critical systems, separate security logging from administrative/IT logging, and lock down log (as it has everything). Monitor with OSSIM (open source). Use intrusion detection, but not just to fulfill a checkbox: build rules from a whitelist perspective (snort). OSSEC has 95% of what you need. Vulnerability management is a QA function when done right: OpenVas and Seccubus are free. Security awareness The reality is users will always click everything. Build real awareness, not compliance driven checkbox, and have it integrated into the culture. Pen test by crowd sourcing—test with logging COSSP http://www.cossp.org/ - Comprehensive Open Source Security Project What Journalists Want: The Investigative Reporters' Perspective on Hacking Dave Maas, San Diego CityBeat Jason Leopold, Truthout.org The difference between hackers and investigative journalists: For hackers, the motivation varies, but method is same, technological specialties. For investigative journalists, it's about one thing—The Story, and they need broad info-gathering skills. J-School in 60 Seconds: Generic formula: Person or issue of pubic interest, new info, or angle. Generic criteria: proximity, prominence, timeliness, human interest, oddity, or consequence. Media awareness of hackers and trends: journalists becoming extremely aware of hackers with congressional debates (privacy, data breaches), demand for data-mining Journalists, use of coding and web development for Journalists, and Journalists busted for hacking (Murdock). Info gathering by investigative journalists include Public records laws. Federal Freedom of Information Act (FOIA) is good, but slow. California Public Records Act is a lot stronger. FOIA takes forever because of foot-dragging—it helps to be specific. Often need to sue (especially FBI). CPRA is faster, and requests can be vague. Dumps and leaks (a la Wikileaks) Journalists want: leads, protecting ourselves, our sources, and adapting tools for news gathering (Google hacking). Anonomity is important to whistleblowers. They want no digital footprint left behind (e.g., email, web log). They don't trust encryption, want to feel safe and secure. Whistleblower laws are very weak—there's no upside for whistleblowers—they have to be very passionate to do it. Accessibility and Security or: How I Learned to Stop Worrying and Love the Halting Problem Anna Shubina, Dartmouth College Anna talked about how accessibility and security are related. Accessibility of digital content (not real world accessibility). mostly refers to blind users and screenreaders, for our purpose. Accessibility is about parsing documents, as are many security issues. "Rich" executable content causes accessibility to fail, and often causes security to fail. For example MS Word has executable format—it's not a document exchange format—more dangerous than PDF or HTML. Accessibility is often the first and maybe only sanity check with parsing. They have no choice because someone may want to read what you write. Google, for example, is very particular about web browser you use and are bad at supporting other browsers. Uses JavaScript instead of links, often requiring mouseover to display content. PDF is a security nightmare. Executible format, embedded flash, JavaScript, etc. 15 million lines of code. Google Chrome doesn't handle PDF correctly, causing several security bugs. PDF has an accessibility checker and PDF tagging, to help with accessibility. But no PDF checker checks for incorrect tags, untagged content, or validates lists or tables. None check executable content at all. The "Halting Problem" is: can one decide whether a program will ever stop? The answer, in general, is no (Rice's theorem). The same holds true for accessibility checkers. Language-theoretic Security says complicated data formats are hard to parse and cannot be solved due to the Halting Problem. W3C Web Accessibility Guidelines: "Perceivable, Operable, Understandable, Robust" Not much help though, except for "Robust", but here's some gems: * all information should be parsable (paraphrasing) * if not parsable, cannot be converted to alternate formats * maximize compatibility in new document formats Executible webpages are bad for security and accessibility. They say it's for a better web experience. But is it necessary to stuff web pages with JavaScript for a better experience? A good example is The Drudge Report—it has hand-written HTML with no JavaScript, yet drives a lot of web traffic due to good content. A bad example is Google News—hidden scrollbars, guessing user input. Solutions: Accessibility and security problems come from same source Expose "better user experience" myth Keep your corner of Internet parsable Remember "Halting Problem"—recognize false solutions (checking and verifying tools) Stop Patching, for Stronger PCI Compliance Adam Brand, protiviti @adamrbrand, http://www.picfun.com/ Adam talked about PCI compliance for retail sales. Take an example: for PCI compliance, 50% of Brian's time (a IT guy), 960 hours/year was spent patching POSs in 850 restaurants. Often applying some patches make no sense (like fixing a browser vulnerability on a server). "Scanner worship" is overuse of vulnerability scanners—it gives a warm and fuzzy and it's simple (red or green results—fix reds). Scanners give a false sense of security. In reality, breeches from missing patches are uncommon—more common problems are: default passwords, cleartext authentication, misconfiguration (firewall ports open). Patching Myths: Myth 1: install within 30 days of patch release (but PCI §6.1 allows a "risk-based approach" instead). Myth 2: vendor decides what's critical (also PCI §6.1). But §6.2 requires user ranking of vulnerabilities instead. Myth 3: scan and rescan until it passes. But PCI §11.2.1b says this applies only to high-risk vulnerabilities. Adam says good recommendations come from NIST 800-40. Instead use sane patching and focus on what's really important. From NIST 800-40: Proactive: Use a proactive vulnerability management process: use change control, configuration management, monitor file integrity. Monitor: start with NVD and other vulnerability alerts, not scanner results. Evaluate: public-facing system? workstation? internal server? (risk rank) Decide:on action and timeline Test: pre-test patches (stability, functionality, rollback) for change control Install: notify, change control, tickets McAfee Secure & Trustmarks — a Hacker's Best Friend Jay James, Shane MacDougall, Tactical Intelligence Inc., Canada "McAfee Secure Trustmark" is a website seal marketed by McAfee. A website gets this badge if they pass their remote scanning. The problem is a removal of trustmarks act as flags that you're vulnerable. Easy to view status change by viewing McAfee list on website or on Google. "Secure TrustGuard" is similar to McAfee. Jay and Shane wrote Perl scripts to gather sites from McAfee and search engines. If their certification image changes to a 1x1 pixel image, then they are longer certified. Their scripts take deltas of scans to see what changed daily. The bottom line is change in TrustGuard status is a flag for hackers to attack your site. Entire idea of seals is silly—you're raising a flag saying if you're vulnerable.

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  • T-SQL Tuesday #005: Creating SSMS Custom Reports

    - by Mike C
    This is my contribution to the T-SQL Tuesday blog party, started by Adam Machanic and hosted this month by Aaron Nelson . Aaron announced this month's topic is "reporting" so I figured I'd throw a blog up on a reporting topic I've been interested in for a while -- namely creating custom reports in SSMS. Creating SSMS custom reports isn't difficult, but like most technical work it's very detailed with a lot of little steps involved. So this post is a little longer than usual and includes a lot of...(read more)

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  • T-SQL Tuesday #005: Creating SSMS Custom Reports

    - by Mike C
    This is my contribution to the T-SQL Tuesday blog party, started by Adam Machanic and hosted this month by Aaron Nelson . Aaron announced this month's topic is "reporting" so I figured I'd throw a blog up on a reporting topic I've been interested in for a while -- namely creating custom reports in SSMS. Creating SSMS custom reports isn't difficult, but like most technical work it's very detailed with a lot of little steps involved. So this post is a little longer than usual and includes a lot of...(read more)

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  • Deeper Integration with phpBB

    - by The Official Microsoft IIS Site
    More good news on the Interoperability front: the new phpBB release is now available for installation from the Windows Web Application Gallery and Web Platform Installer (Web PI) for Windows, IIS and SQL Server. Version 3.0.7-PL1 of phpBB takes advantage of a number of features for PHP applications on the Microsoft Web Platform with Windows, IIS and SQL Server, including SQL Server Driver for PHP 1.1 , which provides key interoperability for PHP applications to use SQL Server or SQL Azure for data...(read more)

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  • C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

    - by James Michael Hare
    Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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  • Tom's Definitive Linux Software Roundup: Office Apps

    <b>Tom's Hardware:</b> "Having covered Linux installation, running Windows XP in Ubuntu, Internet applications, and a handful of open source communications titles, Adam Overa is back with a comprehensive look at office apps for Windows users considering a switch to Linux."

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  • The pros and cons of learning

    - by AaronBertrand
    This week I am at a training course put on by Paul Randal ( blog | twitter ) and Kimberly Tripp ( blog | twitter ) entitled " SQL Immersion ." It is essentially a 5-day deep dive into some of the more important bowels of the Microsoft SQL Server 2008 Internals book they co-wrote with Kalen Delaney, Adam Machanic and Conor Cunningham - with a lot of extra information, insight, experience and interactivity thrown in. I am seeing a lot of benefits from this already. The additional insight around what's...(read more)

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  • Silverlight Cream for April 17, 2010 -- #839

    - by Dave Campbell
    In this Issue: ITLackey, SilverLaw, Max Paulousky, Alex Yakhnin, Paul Sheriff, Douglas, Jeremy Likness, Tomasz Janczuk, Anoop Madhusudanan, Adam Kinney, and Ashish Shetty. Shoutout: If you haven't already seen it, CrocusGirl did a great job of summarizing Day 2 of DevConnections with her Silverlight 4 Launch Notes From SilverlightCream.com: RIA Services - IIS6 Virtual Directory Deployment ITLackey has a post up building on his previous post on Windows Authentication with RIA Services and discusses deploying to an IIS Virtual Directory. How To: Determine ChildWindow Position At Runtime - Silverlight 3 SilverLaw has a post up about determining the position of a ChildWindow at run-time, for example after the user moves it. Modularity in Silverlight Applications - An Issue With ModuleInitializeException – Part 2 Max Paulousky has part 2 of his series up on Modularity in Silverlight... he discusses using XAML as a catalog and registering modules at runtime, and compares to WPF. Creating LINQ Data Provider for WP7 (Part 1) Alex Yakhnin has a first cut at a LINQ Data Provider for WP7 ... I was expecting this to hit pretty soon, because we're all going to want it... check out the code and d/l the project. Synchronize Data between a Silverlight ListBox and a User Control Paul Sheriff demonstrates databinding in XAML between local data in a ListBox and a UserControl. The beginnings of Silverlight development with Expression Blend Douglas has a good post up on beginning your Silverlight development with Expression Blend. He covers a lot of ground in this post. Converting Silverlight 3 to Silverlight 4 Jeremy Likness has a video up demonstrating converting Silverlight 3 to Silverlight 4 with download links and also using commanding on buttons. Debugging WCF RIA Services with WCF traces Tomasz Janczuk has a post up discussing the use of WCF RIA Services traces to help diagnose and debug problems in a deployed service. Bing Maps + oData + Windows Phone 7 - Nerd Dinner Client For Windows Phone 7 Check out what Anoop Madhusudanan has provided... Nerd Dinner for WP7, including OData and BingMaps... just very cool! A few cool new features added in Expression Blend 4 RC Adam Kinney announced the availability of the new Expression Blend and highlights some of the new features... like MakeLayoutPath... FTW! Of Crashing and Sometimes Burning Ashish Shetty has a discourse posted about where the causes of errors might come from, what to expect from the platform, where to find crash dumps, and links to more reading. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Week in Geek: New Security Hole Found in Windows 8 UEFI ‘Secure Boot’

    - by Asian Angel
    This week’s edition of WIG is filled with news link coverage on topics such as Virgin Mobile USA customers are vulnerable to a password security flaw, Google Chrome will use a single profile on Windows 8, the Raspberry Pi gets a turbo mode, and more. How To Create a Customized Windows 7 Installation Disc With Integrated Updates How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using?

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  • T-SQL Tuesday #13 : Business Expectations

    - by AaronBertrand
    This month's T-SQL Tuesday is being hosted by Steve Jones ( @way0utwest ) over at SQLServerCentral . For some history on T-SQL Tuesday, see Adam Machanic's posts here and here . The topic this time is summarized as: "What issues have you had in interacting with the business to get your job done." Over the past 13 years, I've worked primarily on Software as a Service (SaaS) applications. A good portion of my day-to-day grind involved improving or pre-empting scale, but the next largest component of...(read more)

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  • Silverlight Cream for April 20, 2010 -- #842

    - by Dave Campbell
    In this Issue: Zoltan Arvai, Svetla Stoycheva, Alexey Zakharov, Chris Rouw, David Anson(-2-), Bill Reiss, John Papa and Adam Kinney, Chris Klug, CorrinaB, and Mike Snow. Shoutouts: Pete Brown interviewed David Kelley at MIX10: Pete at MIX10: David Kelley on the Prototype WPF and Silverlight Retail Experience Pete Brown also interviewed Emil Stoychev at MIX10: Pete at MIX10: Emil Stoychev on the CompletIT Silverlight Site SilverlightShow has a MIX10 Review by SilverlightShow Live Reporter Cigdem Patlak SilverlightShow also has an Interview with SilverlightShow Article Author Andrej Tozon From SilverlightCream.com: Implementing Push Notifications in Windows Phone 7 Zoltan Arvai has a post up on SilverlightShow discussing Push Notification on WP7 ... what it is, and how to use it. Completit.com - the challenges behind building a corporate website in Silverlight Svetla Stoycheva shows off the new CompleteIT corporate website which is pretty darn cool... and disucusses some of the challenges and solutions Introducing to Halcyone - Silverlight Application Framework: Silverlight Rest Extensions Alexey Zakharov has a tutorial up on a Silverlight application framework he's working on called Halcyone which is available on CodePlex Using the Tag Property during Silverlight Binding Chris Rouw details his SL3 to SL4 conversion and some issues he had, and how he was able to resolve a binding problem using the tag property. Using ContextMenu to implement SplitButton and MenuButton for Silverlight (or WPF) David Anson has a cool discussion up of using the ContextMenu code he put up previously to build a Split button, and includes all the code as usual. Silverlight/WPF Data Visualization Development Release 4 and Windows Phone 7 Charting sample! David Anson updated his Data Visualization because of the new releases, and this time he's including WP7... charting in WP7... ! Space Rocks game step 10: More fun with rocks In episode 10, Bill Reiss shows how to deal with multiple asteroids and all the interaction. Silverlight Training Course (Silverlight 4) Get your serious Silverlight 4 Mojo on with a new SL4 Training kit on Channel 9 ... buncha folks, spearheaded (it looks like) by John Papa and Adam Kinney... Plug-ins and composite applications in Silverlight – pt 3 Chris Klug is back with part 3 of his series on extensions and plug-in loading. So far he's covered a roll-your-own concept and MEF, now he digs into Prism. Transitions, Animations, and Effects with Blend - Part One How cool to have CorrinaB speak at your User Group meeting! ... She did just that in Portland, and instead of simply dropping a deck and some code in her blog, she's giving the run-down on her presentation... always good stuff, Corrina! Tip of the Day #110 – Using Static Resources in Class Libraries Mike Snow's latest tip is about how to create and use a Resource Dictionary. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • links for 2010-04-20

    - by Bob Rhubart
    smattoon@: Enterprise Architecture for Drupal | DrupalCon San Francisco 2010 Details on today's (4/20/10) Drupalcon presentation by Scott "@smattoon" Mattoon. (tags: oracle sun enterprisearchitecture drupal) Mona Rakibe: Deploying BAM Data Control Application to WLS server "Typically we would test our ADF pages that use BAM Data control using integrated WLS server (ADRS), " writes Mona Rakibe. "If we have to deploy this same application to a standalone WLS we have to make sure we have the BAM server connection created in WLS. Unless we do that we may face runtime errors." (tags: oracle otn weblogic soa adf) George Maggessy: Deploying an Consuming Task Flows as Shared Libraries on WLS "A Java EE library is an easy way to share one or more different types of Java EE modules among multiple Enterprise Applications," says George Maggessy. "A shared Java EE library can be a simple jar file, an EJB module or even a web application module." His post includes a sample. (tags: oracle otn architect java weblogic) Adam Hawley: Oracle VM and JRockit Virtual Edition: Oracle Introduces Java Virtualization Solution for Oracle(R) WebLogic Suite Adam Hawley offers information on "a WebLogic Suite option that permits the Oracle WebLogic Server 11g to run on a Java JVM (JRockit Virtual Edition) that itself runs directly on the Oracle VM Server for x86 / x64 without needing any operating system." (tags: oracle otn weblogic virtualization architect javajrockit) @fteter: Highlights From The Bright Lights - Sunday #c10 "Sunday, the first day of Collaborate 10, was probably the best conference kickoff I've ever experienced," says Oracle ACE Director Floyd Teter. "And that's mostly because 'Oracle Fusion Architecture: Soup To Nuts' absolutely rocked!" (tags: oracle otn oracleace collaborate2010 fusionmiddleware architecture) @ORACLENERD: COLLABORATE: Day 2 Wrap Up Oracle ACE Chet "oraclenerd" Justice's tale of cell phone chargers, beer, and shrimp eyes. (tags: oracle otn oracleace collaborate2010) Registration is Open: Oracle Technology Network Architect Day: Dallas The 2010 series of Oracle Technology Network Architect Days kicks off in Dallas on Wednesday, May 13. Registration is now open for the Dallas event, and will open soon for the events in Anaheim, CA and Redwood Shores, CA. (tags: oracle otn architect entarch community events)

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  • 2011 PASS Board Applicants: Kendal Van Dyke

    - by andyleonard
    Introduction I am interviewing 2011 PASS Board Nominee Applicants. As listed on the PASS Board Elections site the applicants are: Rob Farley Geoff Hiten Adam Jorgensen Denise McInerney Sri Sridharan Kendal Van Dyke I'm asking everyone the same questions and blogging the responses in the order received. Kendal Van Dyke is next up: Interview With Kendal Van Dyke 1. What's your day job? I'm a Senior Technical Consultant with Insource Technologies ( http://www.insource.com/ ) in Houston, TX (but I work...(read more)

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  • Dartisans Ep. 6 - Meet the community - Dart hangout

    Dartisans Ep. 6 - Meet the community - Dart hangout In this episode of Dartisans, we are joined by special guests from the Dart community. John Evans, Adam Smith, Chris Buckett, John McCutchan, and Lars Tackmann talk about their Dart libraries, what they like about Dart, and what they want to see in the future. Get started with Dart at www.dartlang.org From: GoogleDevelopers Views: 4 0 ratings Time: 48:11 More in Science & Technology

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  • MIX 2010 recap podcast

    - by Chris Williams
    from www.slickthought.net: Spaghetti Code Podcast: Recapping the MIX Conference 4/2/2010 11:06:10 AM Spaghetti Code (Jeff Brand) is joined by Mike Hodnic, Jason Bock, Adam Grocholski and Chris Williams to share their thoughts and impressions from the Microsoft MIX Conference and their thoughts on Windows Phone, Silverlight 4, and more. Direct Download - click here Subscribe - click here iTunes - click here

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  • Silverlight Cream for June 16, 2010 -- #884

    - by Dave Campbell
    In this Issue: Zoltan Arvai, Emiel Jongerius, Charles Petzold, Adam Kinney, Deepesh Mohnani, Timmy Kokke, and Damon Payne. Shoutouts: Andy Beaulieu reported his Coding4Fun: Shuffleboard Game for WP7 has been posted -- Big ol' Tutorial and 6 videos of WP7 goodness Karl Shifflett announced Three New WPF and Silverlight Designer Videos Posted Charles Petzold has a cool Flip-Number Clock in Silverlight posted... cool demo, and the source. From SilverlightCream.com: Data Driven Applications with MVVM Part II: Messaging, Unit Testing, and Live Data Sources Zoltan Arvai has part 2 of his Data-Driven Apps with MVVM up, and this one is also including Messaging, Unit Testing, and Live WCF Data... good tutorial and all the code. Silverlight DataContext Changed Event and Trigger Emiel Jongerius takes a hard swing at the lack of DataContextChanged... his solution involves two attached properties instead of one... check it out and see what you think! Orientation Strategies for Windows Phone 7 Charles Petzold is discussing WP7 Orientation... showing the problems you can get involved in, and how to work through them... and you might be surprised at how he does it :) ... pretty cool as usual, Charles! Debugging the TranslateZoomRotate WPF Behavior in Blend Adam Kinney talks through a bug reported about the WPF TranslateZoomRotate Behavior. Again, it's WPF, but it's in Blend, and ya never know when the solution might apply. I want my app to look like the Zune client Deepesh Mohnani demonstrates using the Cosmopolitan theme to get his app to have the same look as the Zune client. MVVM Project and Item Templates Timmy Kokke is continuing with his cool SilverAmp media player, using it to expand upon the new Blend and Silverlight 4 features. This episode touches very lightly on cranking up a new MVVM project in Blend. Great Features for MVVM Friendly Objects Part 0: Favor Composition Over Inheritance Damon Payne has the first part up of a series he's working on with 'MVVM Friendly' features... he's building out a lot of the infrastructure in this post for the ones that follow... all good stuff. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • 5 Reasons why I hate WPF

    - by Richard Mitchell
    I decided to use writing a new tool as a way to learn WPF and MVVM and I thought I'd write down a few of my problems as a way of cathartic release. I decided to read a book before attempting WPF for the first time as I've heard others complain about the steep learning curve. I chose the rather excellent "WPF 4 Unleashed" by Adam Nathan to read through and "Pro WPF in C# 2010" by Matthew MacDonald as a reference whilst I programmed. 1 - Poor editing support for XAML The first thing I think any...(read more)

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  • Collide with rotation of the object

    - by Lahiru
    I'm developing a mirror for lazer beam(Ball sprite). There I'm trying to redirect the laze beam according to the ration degree of the mirror(Rectangle). How can I collide the ball to the correct angle if the colliding object is with some angle(45 deg) rather than colliding back. here is an screen shot of my work here is my code using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace collision { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D ballTexture; Rectangle ballBounds; Vector2 ballPosition; Vector2 ballVelocity; float ballSpeed = 30f; Texture2D blockTexture; Rectangle blockBounds; Vector2 blockPosition; private Vector2 origin; KeyboardState keyboardState; //Font SpriteFont Font1; Vector2 FontPos; private String displayText; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here ballPosition = new Vector2(this.GraphicsDevice.Viewport.Width / 2, this.GraphicsDevice.Viewport.Height * 0.25f); blockPosition = new Vector2(this.GraphicsDevice.Viewport.Width / 2, this.GraphicsDevice.Viewport.Height /2); ballVelocity = new Vector2(0, 1); base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); ballTexture = Content.Load<Texture2D>("ball"); blockTexture = Content.Load<Texture2D>("mirror"); //create rectangles based off the size of the textures ballBounds = new Rectangle((int)(ballPosition.X - ballTexture.Width / 2), (int)(ballPosition.Y - ballTexture.Height / 2), ballTexture.Width, ballTexture.Height); blockBounds = new Rectangle((int)(blockPosition.X - blockTexture.Width / 2), (int)(blockPosition.Y - blockTexture.Height / 2), blockTexture.Width, blockTexture.Height); origin.X = blockTexture.Width / 2; origin.Y = blockTexture.Height / 2; // TODO: use this.Content to load your game content here Font1 = Content.Load<SpriteFont>("SpriteFont1"); FontPos = new Vector2(graphics.GraphicsDevice.Viewport.Width - 100, 20); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> /// private float RotationAngle; float circle = MathHelper.Pi * 2; float angle; protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); // TODO: Add your update logic here //check for collision between the ball and the block, or if the ball is outside the bounds of the screen if (ballBounds.Intersects(blockBounds) || !GraphicsDevice.Viewport.Bounds.Contains(ballBounds)) { //we have a simple collision! //if it has hit, swap the direction of the ball, and update it's position ballVelocity = -ballVelocity; ballPosition += ballVelocity * ballSpeed; } else { //move the ball a bit ballPosition += ballVelocity * ballSpeed; } //update bounding boxes ballBounds.X = (int)ballPosition.X; ballBounds.Y = (int)ballPosition.Y; blockBounds.X = (int)blockPosition.X; blockBounds.Y = (int)blockPosition.Y; keyboardState = Keyboard.GetState(); float val = 1.568017f/90; if (keyboardState.IsKeyDown(Keys.Space)) RotationAngle = RotationAngle + (float)Math.PI; if (keyboardState.IsKeyDown(Keys.Left)) RotationAngle = RotationAngle - val; angle = (float)Math.PI / 4.0f; // 90 degrees RotationAngle = angle; // RotationAngle = RotationAngle % circle; displayText = RotationAngle.ToString(); base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here spriteBatch.Begin(); // Find the center of the string Vector2 FontOrigin = Font1.MeasureString(displayText) / 2; spriteBatch.DrawString(Font1, displayText, FontPos, Color.White, 0, FontOrigin, 1.0f, SpriteEffects.None, 0.5f); spriteBatch.Draw(ballTexture, ballPosition, Color.White); spriteBatch.Draw(blockTexture, blockPosition,null, Color.White, RotationAngle,origin, 1.0f, SpriteEffects.None, 0f); spriteBatch.End(); base.Draw(gameTime); } } }

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  • How can I automatically switch to USB headset when plugged in?

    - by d3vid
    Whenever I plugged in my old audio jack headset, sound was immediately diverted from my speakers to the headset speakers, and the microphone was immediately available. When I plug in my new USB headset, I have to open Sound Preferences and switch both input and output to the headset. Is there any way to make this happen automatically? I'm using a Fujitsu-Siemens Amilo Pi laptop, Maverick and a Logitech H330 USB headset.

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