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  • I have applied a check for not allowing alphabets.But its not working.....

    - by bhavna raghuvanshi
    import java.util.Scanner; public class Main extends Hashmap{ public static void main(String[] args) { Hashmap hm = new Hashmap(); int x=0; Scanner input = new Scanner(System.in); do{ System.out.print("Enter any integer value between 1 to 12: "); x = input.nextInt(); }while(x<=0 || x>12); Scanner sc = new Scanner(System.in); //int number; do { while (!sc.hasNextInt()) { System.out.println("That's not a number!"); sc.next(); } x = sc.nextInt(); }while(x>=0); String month = hm.getEntry(x); System.out.println(month); } } here I need to restrict user from entering an alphabet.But its not working. pls help...

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  • Help Forming An SQL Query That Selects The Max Difference Of Two Fields

    - by Frank
    I'm trying to select a record with the most effective votes. Each record has an id, the number of upvotes (int) and the number of downvotes (int) in a MySQL database. I know basic update, select, insert queries but I'm unsure of how to form a query that looks something like: SELECT * FROM topics WHERE MAX(topic.upvotes - topic.downvotes). Please excuse my made up SQL. The tutorials on SQL I find on the internet cover very basic stuff. Does anyone recommend a good book on this subject?

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  • I need to speed this code at least 2 times!

    - by Dominating
    include include include include using namespace std; inline void PrintMapName(multimap pN, string s) { pair::iterator, multimap::iterator ii; multimap::iterator it; ii = pN.equal_range(s); multimap tmp; for(it = ii.first; it != ii.second; ++it) { tmp.insert(pair(it-second,1)); } multimap::iterator i; bool flag = false; for(i = tmp.begin(); i != tmp.end(); i++) { if(flag) { cout<<" "; } cout<first; if(flag) { cout<<" "; } flag = true; } cout< int main() { multimap phoneNums; multimap numPhones; int N; cinN; int tests; string tmp, tmp1,tmp2; while(N 0) { cintests; while(tests 0) { cintmp; if(tmp == "add") { cintmp1tmp2; phoneNums.insert(pair(tmp1,tmp2)); numPhones.insert(pair(tmp2,tmp1)); } else { if(tmp == "delnum") { cintmp1; multimap::iterator it; multimap::iterator tmpr; for(it = phoneNums.begin(); it != phoneNums.end();it++) { tmpr = it; if(it-second == tmp1) { phoneNums.erase(it,tmpr); } } numPhones.erase(tmp1); } else { if(tmp == "delname") { cintmp1; phoneNums.erase(tmp1); multimap::iterator it; multimap::iterator tmpr; for(it = numPhones.begin(); it != numPhones.end();it++) { tmpr = it; if(it-second == tmp1) { numPhones.erase(it,tmpr); } } } else { if(tmp =="queryname") { cintmp1; PrintMapName(phoneNums, tmp1); } else//querynum { cintmp1; PrintMapName(numPhones, tmp1); } } } } tests--; } N--; } return 0; }

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  • java instanceof not finding method

    - by Razvan N
    I have a problem with java instanceof. I have a class called Employee and several others that extend this one, for example - Manager. I also created another class,EmployeeStockPlan, where I wanted to test if instanceof is finding which object I am using. But when I am calling a method from the new class, I have this error: The method grantStock(Manager) is undefined for the type Loader. Sorry, I am somehow new to some thing in java, I hope I am not asking dumb questions. The Employee class: package com.example.domain; public class Employee { private int empId; private String name; private String ssn; private double salary; public Employee(int empId, String name, String ssn, double salary) { // constructor // method; this.empId = empId; this.name = name; this.ssn = ssn; this.salary = salary; } public void setName(String newName) { if (newName != null) { this.name = newName; } } public void raiseSalary(double increase) { this.salary += increase; } public String getName() { return name; } public double getSalary() { return salary; } public String getDetails() { return "Employee id: " + empId + "\n" + "Employee name: " + name; } } The Manager class: package com.example.domain; public class Manager extends Employee { private String deptName; public Manager(int empId, String name, String ssn, double salary, String dept) { super(empId, name, ssn, salary); this.deptName = dept; } public String getDeptName() { return deptName; } public String getDetails() { return super.getDetails() + "\n" + "Department: " + deptName; } } The EmployeeStockPlan class: package com.example.domain; public class EmployeeStockPlan { public void grantStock(Employee e) { // nothing calculated, just simulating; System.out.println("This is an employee!"); if (e instanceof Manager) { // process Manager stock grant System.out.println("This is a manager!"); } else { // error - instance of Engineer? System.out.println("Not an engineer!"); } return; } } The main class: EmployeeStockPlan esp = new EmployeeStockPlan(); Manager m = new Manager (12421, "Manager1", "111-4254-521", 2430, "Marketing1"); grantStock(m);

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  • Cannot initialize non-const reference from convertible type

    - by Julien L.
    Hi, I cannot initialize a non-const reference to type T1 from a convertible type T2. However, I can with a const reference. long l; const long long &const_ref = l; // fine long long &ref = l; // error: invalid initialization of reference of // type 'long long int&' from expression of type // 'long int' Most problems I encountered were related to r-values that cannot be assigned to a non-const reference. This is not the case here -- can someone explain? Thanks.

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  • Asp.net razor textbox array for list items

    - by yycdev
    I can't find or figure out how to take a list of items (cupcakes) and display them in razor with a quantity field. What is happening is I am not able to get the values for each cupcake quantity in the list. Can you do textbox arrays in Razor? VIEW <div class="form-group"> <label>Cupcakes</label> @foreach (var cupcake in Model.CupcakeList) { @Html.TextBox("CupcakeQuantities", cupcake.Id) @cupcake.Name <br/> } </div> MODEL public List<Cupcake> CupcakeList { get; set; } public List<int> CupcakeQuantities { get; set; } CONTROLLER public ActionResult Create() { var model = new PartyBookingModel() { CupcakeList = db.Cupcakes.ToList(), CupcakeQuantities = new List<int>() }; return View(model); }

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  • what is value of x for load and store

    - by Kevinniceguy
    This is some challenge On a single processor system, in which load and store are assumed to be atomic, what are all the possible values for x after both threads have completed in the following execution, assuming that x is initialised to O? Hint: you need to consider how this code might be compiled into machine language. for (int i = 0; i < 5; i++) : x = x + 1; for (int j = 0; j < 5; j++) : x = x + 1;

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  • Speed up multiple JDBC SQL querys?

    - by paddydub
    I'm working on a shortest path a* algorithm in java with a mysql db. I'm executing the following SQL Query approx 300 times in the program to find route connections from a database of 10,000 bus connections. It takes approx 6-7 seconds to execute the query 300 times. Any suggestions on how I can speed this up or any ideas on a different method i can use ? Thanks ResultSet rs = stmt.executeQuery("select * from connections" + " where Connections.From_Station_stopID ="+StopID+";"); while (rs.next()) { int id = rs.getInt("To_Station_id"); String routeID = rs.getString("To_Station_routeID"); Double lat = rs.getDouble("To_Station_lat"); Double lng = rs.getDouble("To_Station_lng"); int time = rs.getInt("Time"); }

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  • C++ initializing constants and inheritance

    - by pingvinus
    I want to initialize constant in child-class, instead of base class. And use it to get rid of dynamic memory allocation (I know array sizes already, and there will be a few child-classes with different constants). So I try: class A { public: const int x; A() : x(0) {} A(int x) : x(x) {} void f() { double y[this->x]; } }; class B : A { B() : A(2) {} }; Pretty simple, but compiler says: error C2057: expected constant expression How can I say to compiler, that it is really a constant?

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  • How do you write an idiomatic Scala Quicksort function?

    - by Don Mackenzie
    I recently answered a question with an attempt at writing a quicksort function in scala, I'd seen something like the code below written somewhere. def qsort(l: List[Int]): List[Int] = { l match { case Nil => Nil case pivot::tail => qsort(tail.filter(_ < pivot)) ::: pivot :: qsort(tail.filter(_ >= pivot)) } } My answer received some constructive criticism pointing out that List was a poor choice of collection for quicksort and secondly that the above wasn't tail recursive. I tried to re-write the above in a tail recursive manner but didn't have much luck. Is it possible to write a tail recursive quicksort? or, if not, how can it be done in a functional style? Also what can be done to maximise the efficiency of the implementation? Thanks in advance.

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  • multiple C++ deletion of a memory pointed by multiple objects

    - by elgcom
    Another c++ pointer deletion question is in the following example: class Foo { public: int *p; ~Foo() { delete p; p = NULL; } }; Foo *f1 = new Foo(); Foo *f2 = new Foo(); f1->p = new int(1); f2->p = f1->p; delete f2; // ok delete f1; // no error? Why I did not get error when calling "delete f1"? didn't I delete the same address (*p) twice? If I directly delete the pointers in the last 2 lines of code, I will get error. delete f2->p; // ok delete f1->p; // error!! *** glibc detected *** double free or corruption (fasttop) ***

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  • Autocorrelation method for pitch determination.. whats d input data form..?

    - by harsh
    i hav read a code for pitch determination using autocorrelation method. can anybody please tell wht wud b d input data(passed as argument to DetectPitch()) function here: double DetectPitch(short* data) { int sampleRate = 2048; //Create sine wave double *buffer = malloc(1024*sizeof(short)); double amplitude = 0.25 * 32768; //0.25 * max length of short double frequency = 726.0; for (int n = 0; n < 1024; n++) { buffer[n] = (short)(amplitude * sin((2 * 3.14159265 * n * frequency) / sampleRate)); } doHighPassFilter(data); printf("Pitch from sine wave: %f\n",detectPitchCalculation(buffer, 50.0, 1000.0, 1, 1)); printf("Pitch from mic: %f\n",detectPitchCalculation(data, 50.0, 1000.0, 1, 1)); return 0; }

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  • Remove items from SWT tables

    - by Dima
    This is more of an answer I'd like to share for the problem I was chasing for some time in RCP application using large SWT tables. The problem is the performance of SWT Table.remove(int start, int end) method. It gives really bad performance - about 50msec per 100 items on my Windows XP. But the real show stopper was on Vista and Windows 7, where deleting 100 items would take up to 5 seconds! Looking into the source code of the Table shows that there are huge amount of windowing events flying around in this call.. That brings the windowing system to its knees. The solution was to hide the damn thing during this call: table.setVisible(false); table.remove(from, to); table.setVisible(true); That does wonders - deleting 500 items on both XP & Windows7 takes ~15msec, which is just an overhead for printing out time stamps I used. nice :)

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  • Calling a function that has 'Activity' as an argument.

    - by Andrew
    I have stripped down my functions for simplicity: public static int countLines(String fileName, Activity activity) throws IOException { BufferedReader in = new BufferedReader(new InputStreamReader(activity.getAssets().open(fileName))); return 3; } I am calling it from here: private CharSequence RandomRead() throws IOException { int numberLines = countLines("data.txt", ??????); return "Success" } In the call to countLines("data.txt", ??????), what do I put as the argument for the Activity? I've Googled all night and I can find no examples of an actual call to a function where Activity is an argument. (Lots of examples actually using 'activity', but no calls to the example functions). Thanks!

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  • How can i get the correct date?

    - by Haley
    Hi, I have a time of NSString type. i wonder get the day, but i find somethine strange. NSString *strTime = @"2010-05-14 16:00:01"; NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; NSDate *oldDate = [formatter dateFromString:strTime]; unsigned int flags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit; NSCalendar* calendar = [NSCalendar currentCalendar]; NSDateComponents* components = [calendar components:flags fromDate:oldDate]; int day = [components day]; When NSString *strTime = @"2010-05-14 16:00:01" the day is 15,and when NSString *strTime = @"2010-05-14 16:00:00" the day is 14.I want to know why?

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  • EF4: common interface for EF entities

    - by Feryt
    Hi. I have public interface: public interface IEntity { int ID { get; set; } string Name { get; set; } bool IsEnabled { get; set; } } ehich some EF entities implements(thanks to partial class) and extesion method: public static IEnumerable<SelectListItem> ToSelectListItems<T>(this IQueryable<T> entities, int? selectedID = null) where T : IEntity { return entities.Select(c => new { c.Name, c.ID }).ToList().Select(c => new SelectListItem { Text = c.Name, Value = c.ID.ToString(), Selected = (c.ID == selectedID) }); } Calling ToSelectListItems return exception: Unable to cast the type '<EF entity name>' to type 'IEntity'. LINQ to Entities only supports casting Entity Data Model primitive types. Why, any ideas? Thank you.

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  • java - how to split string in to multiple parts?

    - by Ewen
    I have a string that contains a value "firstword second third", and an ArrayList. I want to split the whole string in to by spaces and add the splitted strings in to the ArrayList. For example,"firstword second third" can be split to three separate strings and added three times in to the ArrayList. "1 2 3 4" can be splitted in to 4 strings and added 4 times in to the ArrayList. See the code below: public void separateAndAdd(String notseparated) { for(int i=0;i<canBeSepartedinto(notseparated);i++{ //what should i put here in order to split the string via spaces? thearray.add(separatedstring); } } public int canBeSeparatedinto(String string) //what do i put here to find out the amount of spaces inside the string? return .... } Please leave a comment if you dont get what I mean or I should fix some errors in this post. Thanks for your time!

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  • Parenthesis operator in C. What is the effect in the following code

    - by Andre
    Hi everyone, I was playing with a macro to enable/disable traces when I came out with the following code when the macro is disabled: int main { ("Hello world"); } This code is valid and I got the desired effect (nothing happens when the macro is disabled) but I couldn't figure out what exactly is happening. Is the compiler seeing the parenthesis as a "nameless" method declaration? To make it clearer the code is : #ifdef TRACE #define trace printf("%s %d -> ",__FILE__, __LINE__);printf else #define trace #endif int main { trace("Hello world"); } Thanks in advance.

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  • C++'s char * by swig got problem in Python 3.0

    - by gpliu3
    Our C++ lib works fine with Python2.4 using Swig, returning a C++ char* back to a python str. But this solution hit problem in Python3.0, error is: Exception=(, UnicodeDecodeError('utf8', b"\xb6\x9d\xa.....",0, 1, 'unexpected code byte') Our definition is like(working fine in Python 2.4): void cGetPubModulus( void* pSslRsa, char* cMod, int* nLen ); %include "cstring.i" %cstring_output_withsize( char* cMod, int* nLen ); Suspect swig is doing a Bytes-Str conversion automatically. In python2.4 it can be implicit but in Python3.0 it's no long allowed.. Anyone got a good idea? thanks

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  • C++ - what does the colon after a constructor mean?

    - by waitinforatrain
    I'd happily Google this but don't know what to call it to Google it. I have a piece of code here: class demo { private: unsigned char len, *dat; public: demo(unsigned char le = 5, unsigned char default) : len(le) { dat = new char[len]; for (int i = 0; i <= le; i++) dat[i] = default; } void ~demo(void) { delete [] *dat; } }; class newdemo : public demo { private: int *dat1; public: newdemo(void) : demo(0, 0) { *dat1 = 0; return 0; } }; (It's from a past exam paper and the question is to correct errors in the code so ignore errors!) My question is, what are the ": len(le) " and " : demo(0, 0)" called? Something to do with inheritance?

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  • SortList duplicated key, but it shouldn't

    - by Luca
    I have a class which implements IList interface. I requires a "sorted view" of this list, but without modifying it (I cannot sort directly the IList class). These view shall be updated when the original list is modified, keeping items sorted. So, I've introduced a SortList creation method which create a SortList which has a comparer for the specific object contained in the original list. Here is the snippet of code: public class MyList<T> : ICollection, IList<T> { ... public SortedList CreateSortView(string property) { try { Lock(); SortListView sortView; if (mSortListViews.ContainsKey(property) == false) { // Create sorted view sortView = new SortListView(property, Count); mSortListViews.Add(property, sortView); foreach (T item in Items) sortView.Add(item); } else sortView = mSortListViews[property]; sortView.ReferenceCount++; return (sortView); } finally { Unlock(); } } public void DeleteSortView(string property) { try { Lock(); // Unreference sorted view mSortListViews[property].ReferenceCount--; // Remove sorted view if (mSortListViews[property].ReferenceCount == 0) mSortListViews.Remove(property); } finally { Unlock(); } } protected class SortListView : SortedList { /// <summary> /// /// </summary> /// <param name="property"></param> /// <param name="capacity"></param> public SortListView(string property, int capacity) : base(new GenericPropertyComparer(typeof(T).GetProperty(property, BindingFlags.Instance | BindingFlags.Public)), capacity) { } /// <summary> /// Reference count. /// </summary> public int ReferenceCount = 0; /// <summary> /// /// </summary> /// <param name="item"></param> public void Add(T item) { Add(item, item); } /// <summary> /// /// </summary> /// <param name="item"></param> public void Remove(T item) { // Base implementation base.Remove(item); } /// <summary> /// Compare object on a generic property. /// </summary> class GenericPropertyComparer : IComparer { #region Constructors /// <summary> /// Construct a GenericPropertyComparer specifying the property to compare. /// </summary> /// <param name="property"> /// A <see cref="PropertyInfo"/> which specify the property to be compared. /// </param> /// <remarks> /// The <paramref name="property"/> parameter imply that the compared objects have the specified property. The property /// must be readable, and its type must implement the IComparable interface. /// </remarks> public GenericPropertyComparer(PropertyInfo property) { if (property == null) throw new ArgumentException("property doesn't specify a valid property"); if (property.CanRead == false) throw new ArgumentException("property specify a write-only property"); if (property.PropertyType.GetInterface("IComparable") == null) throw new ArgumentException("property type doesn't IComparable"); mSortingProperty = property; } #endregion #region IComparer Implementation public int Compare(object x, object y) { IComparable propX = (IComparable)mSortingProperty.GetValue(x, null); IComparable propY = (IComparable)mSortingProperty.GetValue(y, null); return (propX.CompareTo(propY)); } /// <summary> /// Sorting property. /// </summary> private PropertyInfo mSortingProperty = null; #endregion } } /// <summary> /// Sorted views of this ReactList. /// </summary> private Dictionary<string, SortListView> mSortListViews = new Dictionary<string, SortListView>(); } Practically, class users request to create a SortListView specifying the name of property which determine the sorting, and using the reflection each SortListView defined a IComparer which keep sorted the items. Whenever an item is added or removed from the original list, every created SortListView will be updated with the same operation. This seems good at first chance, but it creates me problems since it give me the following exception when adding items to the SortList: System.ArgumentException: Item has already been added. Key in dictionary: 'PowerShell_ISE [C:\Windows\sysWOW64\WindowsPowerShell\v1.0\PowerShell_ISE.exe]' Key being added: 'PowerShell_ISE [C:\Windows\system32\WindowsPowerShell\v1.0\PowerShell_ISE.exe]' As you can see from the exception message, thrown by SortedListView.Add(object), the string representation of the key (the list item object) is different (note the path of the executable). Why SortList give me that exception? To solve this I tried to implement a GetHashCode implementation for the underlying object, but without success: public override int GetHashCode() { return ( base.GetHashCode() ^ mApplicationName.GetHashCode() ^ mApplicationPath.GetHashCode() ^ mCommandLine.GetHashCode() ^ mWorkingDirectory.GetHashCode() ); }

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  • How To? Use an Expression Tree to call a Generic Method when the Type is only known at runtime.

    - by David Williams
    Please bear with me; I am very new to expression trees and lambda expressions, but trying to learn. This is something that I solved using reflection, but would like to see how to do it using expression trees. I have a generic function: private void DoSomeThing<T>( param object[] args ) { // Some work is done here. } that I need to call from else where in my class. Now, normally, this would be be simple: DoSomeThing<int>( blah ); but only if I know, at design time that I am working with an int. When I do not know the type until runtime is where I need the help. Like I said, I know how to do it via reflection, but I would like to do it via expression trees, as my (very limited) understanding is that I can do so. Any suggestions or points to sites where I can get this understanding, preferably with sample code?

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  • Why freed struct in C still has data?

    - by kliketa
    When I run this code: #include <stdio.h> typedef struct _Food { char name [128]; } Food; int main (int argc, char **argv) { Food *food; food = (Food*) malloc (sizeof (Food)); snprintf (food->name, 128, "%s", "Corn"); free (food); printf ("%d\n", sizeof *food); printf ("%s\n", food->name); } I still get 128 Corn although I have freed food. Why is this? Is memory really freed?

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  • .NET SerialPort.Read skipps bytes

    - by Lukas Rieger
    Solution Reading the data byte wise via "port.ReadByte" is too slow, the problem is inside the SerialPort class. i changed it to reading bigger chunks via "port.Read" and there are now no buffer overruns. although i found the solution myself, writing it down helped me and maybe someone else has the same problem and finds this via google... (how can i mark it as answered?) EDIT 2 by setting port.ReadBufferSize = 2000000; i can delay the problem for ~30 seconds. so it seems, .Net really is too slow... since my application is not that critical, i just set the buffer to 20MB, but i am still interested in the cause. EDIT i just tested something i had not thought of before (shame on me): port.ErrorReceived += (object self, SerialErrorReceivedEventArgs se_arg) => { Console.Write("| Error: {0} | ", System.Enum.GetName(se_arg.EventType.GetType(), se_arg.EventType)); }; and it seems that i have an overrun. Is the .Net implementation too slow for 500k or is there an error on my side? Original Question i built a very primitive oszilloscope (avr, which sends adc data over uart to an ftdi chip). On the pc side i have a WPF Programm that displays this data. The Protokoll is: two sync bytes (0xaffe) - 14 data bytes - two sync bytes - 14 data bytes - ... i use 16bit values, so inside the 14 data bytes are 7 channels (lsb first). I verified the uC Firmware with hTerm, and it does send and receive everything correct. But, if i try to read the data with C#, sometimes some bytes are lost. The oszilloscop programm is a mess, but i created a small sample application, which has the same symptoms. I added two extension methods to a) read one byte from the COM Port and ignore -1 (EOF) and b) wait for the sync pattern. The sample programm first syncs onto the data stream by waiting for (0xaffe) and then compares the received bytes with the expected values. the loop runs a few times until an assert failed message pops up. I could not find anything about lost bytes via google, any help would be appreciated. Code using System; using System.Collections.Generic; using System.Diagnostics; using System.IO.Ports; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SerialTest { public static class SerialPortExtensions { public static byte ReadByteSerial(this SerialPort port) { int i = 0; do { i = port.ReadByte(); } while (i < 0 || i > 0xff); return (byte)i; } public static void WaitForPattern_Ushort(this SerialPort port, ushort pattern) { byte hi = 0; byte lo = 0; do { lo = hi; hi = port.ReadByteSerial(); } while (!(hi == (pattern >> 8) && lo == (pattern & 0x00ff))); } } class Program { static void Main(string[] args) { //500000 8n1 SerialPort port = new SerialPort("COM3", 500000, Parity.None, 8, StopBits.One); port.Open(); port.DiscardInBuffer(); port.DiscardOutBuffer(); //Sync port.WaitForPattern_Ushort(0xaffe); byte hi = 0; byte lo = 0; int val; int n = 0; // Start Loop, the stream is already synced while (true) { //Read 7 16-bit values (=14 Bytes) for (int i = 0; i < 7; i++) { lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val != 0xaffe); } //Read two sync bytes lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val == 0xaffe); n++; } } } }

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