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  • Reverse String Error?

    - by R41nB0w M47r1z
    I am creating this revese string App but i get a error if i include a space in the string ! #include <iostream> #include <string> using namespace std; int main() { int inputa; cout<<"%%%%%%%%%%%%%%%%%%String Reversing App%%%%%%%%%%%%%%%%%%%%%%%%"<<endl<<endl; cout<<"\nEnter 1 to continue and 0 to exit"<<endl<<endl; cin>>inputa; if(inputa!=0) { do { string a,c=""; cout<<"\nEnter the string you want to Reverse : "; cin>>a; for(int x=a.length()-1; x>=0; x--) { c=c+a.substr(x,1); } cout<<"\nThe Reverse String is : "<<c<<endl; cout<<"\nEnter 1 to continue and 0 to exit"<<endl<<endl; cin>>inputa; } while(inputa!=0); } //not my home work } If I type the following string like "abc def" there i get an error . But otherwise it works perfectly ! Is there some mistake with the codes ! I am new to CPP so it would be helpful if you could help me !

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  • Strange compiler complaint when using similar code

    - by Jason
    For a project, I have to ask the user for a file name, and I'm reading it in character by character using getchar. From the main, I call the function char *coursename= introPrint(); //start off to print the usage directions and get the first bit of input. That function is defined as char *introPrint(){ int size= 20; int c; int length=0; char buffer[size]; //instructions printout, cut for brevity //get coursename from user and return it while ( (c=getchar()) != EOF && (c != '\n') ){ buffer[length++]= c; if (length==size-1) break; } buffer[length]=0; return buffer; } This is basically identical code I wrote to ask the user for input, replace the character echo with asterisks, then print out the results. Here, though, I'm getting a function returns address of local variable warning for the return statement. So why am I getting no warnings from the other program, but trigger one for this code?

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  • Calling base class constructor

    - by The Void
    In the program below, is the line Derived(double y): Base(), y_(y) correct/allowed? That is, does it follow ANSI rules? #include <iostream> class Base { public: Base(): x_(0) { std::cout << "Base default constructor called" << std::endl; } Base(int x): x_(x) { std::cout << "Base constructor called with x = " << x << std::endl; } void display() const { std::cout << x_ << std::endl; } protected: int x_; }; class Derived: public Base { public: Derived(): Base(1), y_(1.2) { std::cout << "Derived default constructor called" << std::endl; } Derived(double y): Base(), y_(y) { std::cout << "Derived constructor called with y = " << y << std::endl; } void display() const { std::cout << Base::x_ << ", " << y_ << std::endl; } private: double y_; }; int main() { Base b1; b1.display(); Derived d1; d1.display(); std::cout << std::endl; Base b2(-9); b2.display(); Derived d2(-8.7); d2.display(); return 0; }

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  • Simulation tree command in C

    - by Ecle
    I have to create the simulation of tree command in C, this is my current code: #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <dirent.h> #include <string.h> main(int argc, char *argv[]){ int i; if(argc < 2){ printf("\nError. Use: %s directory\n", argv[0]); system("exit"); } for(i=1;i<argc;i++) //if(argv[i][0] != '-') tree(argv[i]); } tree(char *ruta){ DIR *dirp; struct dirent *dp; static nivel = 0; struct stat buf; char fichero[256]; int i; if((dirp = opendir(path)) == NULL){ perror(path); return; } while((dp = readdir(dirp)) != NULL){ printf(fichero, "%s/%s", path, dp->d_name); if((buf.st_mode & S_IFMT) == S_IFDIR){ for(i=0;i<nivel;i++) printf("\t"); printf("%s\n", dp->d_name); ++nivel; tree(fichero); --nivel; } } } Apparently, it works! (due to it compiles correctly) But I don't why. I can't pass the correct arguments to execute this. Thank you so much, people.

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  • Can the size of a structure change after compiled?

    - by Sarah Altiva
    Hi, suppose you have the following structure: #include <windows.h> // BOOL is here. #include <stdio.h> typedef struct { BOOL someBool; char someCharArray[100]; int someIntValue; BOOL moreBools, anotherOne, yetAgain; char someOthercharArray[23]; int otherInt; } Test; int main(void) { printf("Structure size: %d, BOOL size: %d.\n", sizeof(Test), sizeof(BOOL)); } When I compile this piece of code in my machine (32-bit OS) the output is the following: Structure size: 148, BOOL size: 4. I would like to know if, once compiled, these values may change depending on the machine which runs the program. E.g.: if I ran this program in a 64-bit machine, would the output be the same? Or once it's compiled it'll always be the same? Thank you very much, and forgive me if the answer to this question is obvious...

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  • update attribute a element in arraylist on java ?

    - by tiendv
    I have a class Class TextChunks extends Token { ArrayList<Token> arrt = new ArrayList<Token>(); } extent fron class : class Token { String s; int frequency = 1 ;// Tern frequency in TextChunk } Now in token i have arraylist token , i want to update attribute frequency of token in Texchunks when have more than one tokens same . For clearly a give a example : Texchunks :" in particular in domain and range in some " So have 8 token : in,particular,in,domain,and,range,in,some i want update attribute frequency for token : in this example when i get attribute frequency of token "in" must return 3 it mean when i call : get frequency of Texchunks when dislay : in 3 particular 1 in 3 domain 1 and 1 range 1 in 3 some 1 here my code : public TextChunks updateFrequencyOfTokenInTextChunks (TextChunks tc) throws CloneNotSupportedException { TextChunks result = (TextChunks) tc.clone(); for (int i =0 ; i< result.arrt.size() ; i++ ){ int j=i+1; if (result.arrt.get(i).compareTwoToken(result.arrt.get(j))== true ) { // help here how to update attribute result.arrt.get(i) // and result.arrt.get(J) = ++ and } } return tc; } Thanks in advandce

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  • "for" loop from program 7.6 from Kochan's "Programming in Objective-C"

    - by Mr_Vlasov
    "The sigma notation is shorthand for a summation. Its use here means to add the values of 1/2^i, where i varies from 1 to n. That is, add 1/2 + 1/4 + 1/8 .... If you make the value of n large enough, the sum of this series should approach 1. Let’s experiment with different values for n to see how close we get." #import "Fraction.h" int main (int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Fraction *aFraction = [[Fraction alloc] init]; Fraction *sum = [[Fraction alloc] init], *sum2; int i, n, pow2; [sum setTo: 0 over: 1]; // set 1st fraction to 0 NSLog (@"Enter your value for n:"); scanf ("%i", &n); pow2 = 2; for (i = 1; i <= n; ++i) { [aFraction setTo: 1 over: pow2]; sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; pow2 *= 2; } NSLog (@"After %i iterations, the sum is %g", n, [sum convertToNum]); [aFraction release]; [sum release]; [pool drain]; return 0; } Question: Why do we have to create additional variable sum2 that we are using in the "for" loop? Why do we need "release previous sum" here and then again give it a value that we just released? : sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; Is it just for the sake of avoiding memory leakage? (method "add" initializes a variable that is stored in sum2)

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  • Should try...catch go inside or outside a loop?

    - by mmyers
    I have a loop that looks something like this: for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } This is the main content of a method whose sole purpose is to return the array of floats. I want this method to return null if there is an error, so I put the loop inside a try...catch block, like this: try { for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } } catch (NumberFormatException ex) { return null; } But then I also thought of putting the try...catch block inside the loop, like this: for(int i = 0; i < max; i++) { String myString = ...; try { float myNum = Float.parseFloat(myString); } catch (NumberFormatException ex) { return null; } myFloats[i] = myNum; } So my question is: is there any reason, performance or otherwise, to prefer one over the other? EDIT: The consensus seems to be that it is cleaner to put the loop inside the try/catch, possibly inside its own method. However, there is still debate on which is faster. Can someone test this and come back with a unified answer? (EDIT: did it myself, but voted up Jeffrey and Ray's answers)

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  • creating an object within a function of a program

    - by user1066524
    could someone please tell me what I need to do in order to create an object in a function. I will try to explain by making up some sort of example... Let's say I have a program named TimeScheduler.cpp that implements the class Schedule.h (and I have the implementation in a separate file Schedule.cpp where we define the methods). In the declaration file we have declared two constructors Schedule(); //the default and Schedule(int, int, int);//accepts three arguments to get to the point--let's say in the main program file TimeScheduler.cpp we created our own functions in this program apart from the functions inherited from the class Schedule. so we have our prototypes listed at the top. /*prototypes*/ void makeSomeTime(); etc..... we have main(){ //etc etc... } we then define these program functions void makeSomeTime(){ //process } let's say that inside the function makeSomeTime(), we would like to create an array of Schedule objects like this Schedule ob[]={ summer(5,14, 49), fall(9,25,50) }; what do I have to do to the function makeSomeTime() in order for it to allow me to create this array of objects. The reason I ask is currently i'm having difficulty with my own program in that it WILL allow me to create this array of objects in main()....but NOT in a function like I just gave an example of. The strange thing is it will allow me to create a dynamic array of objects in the function..... like Schedule *ob = new Schedule[n+1]; ob[2]= Schedule(x,y,z); Why would it let me assign to a non-dynamic array in main(), but not let me do that in the function?

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  • Why is T() = T() allowed?

    - by Rimo
    I believe the expression T() creates an rvalue (by the Standard). However, the following code compiles (at least on gcc4.0): class T {}; int main() { T() = T(); } I know technically this is possible because member functions can be invoked on temporaries and the above is just invoking the operator= on the rvalue temporary created from the first T(). But conceptually this is like assigning a new value to an rvalue. Is there a good reason why this is allowed? Edit: The reason I find this odd is it's strictly forbidden on built-in types yet allowed on user-defined types. For example, int(2) = int(3) won't compile because that is an "invalid lvalue in assignment". So I guess the real question is, was this somewhat inconsistent behavior built into the language for a reason? Or is it there for some historical reason? (E.g it would be conceptually more sound to allow only const member functions to be invoked on rvalue expressions, but that cannot be done because that might break some existing code.)

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  • Building argv and argc

    - by Wylie Coyote SG.
    I'm a student programmer using Qt to build a GUI application for work. The primary purpose of this application is to open some of our old style files, allows better editing and then save the file in a new format and file extension. Recently I have been asked to allow this conversion to take place from a terminal. While I do know what argv and argc are along with what they represent I am unsure how to accomplish what they want. For instance how to handle relative paths vs. absolute... maybe how to get absolute from relative; perhaps none of that is even needed. My programming experience has been primarily with guis so this is a little new to me. Users would like the following to be ran from the terminal application -o /fileLocation /fileDestination template(to determine new format) I began to use for loops and if statements to begin accomplishing this when I relized that I might be taking the worng approach to all of this. I WOULD ALSO BE REALLY INTERESTED IF QT HAS SOMETHING FOR THIS! Here is what I have began coming up with: int main(int argc, char *argv[]) { if(argc > 1) { for(int i = 0; i < argc; i++) { if(argv[i] == "-c") { QString fileName = QString::fromStdString(argv[i+1]); QString fileDestination = QString::fromStdString(argv[i+2]); QString templateName = QString::fromStdString(argv[i+3]); QFile fileToConvert(fileName); if(fileToConvert.open(QFile::ReadOnly)) { //do stuff Thanks for reading my post and a big thanks for any contributions you make to helping me overcome this issue.

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  • MySql stored procedure not found in PHP

    - by kaupov
    Hello, I have a trouble with MySql stored procedure that calls itself recursively using PHP (CakePHP). Calling it I receive following error: SQL Error: 1305: FUNCTION dbname.GetAdvertCounts does not exist The procedure itself is following: delimiter // DROP PROCEDURE IF EXISTS GetAdvertCounts// CREATE PROCEDURE GetAdvertCounts(IN category_id INT) BEGIN DECLARE no_more_sub_categories, advert_count INT DEFAULT 0; DECLARE sub_cat_id INT; DECLARE curr_sub_category CURSOR FOR SELECT id FROM categories WHERE parent_id = category_id; DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_sub_categories = 1; SELECT COUNT(*) INTO advert_count FROM adverts WHERE category_id = category_id; OPEN curr_sub_category; FETCH curr_sub_category INTO sub_cat_id; REPEAT SELECT advert_count + GetAdvertCounts(sub_cat_id) INTO advert_count; FETCH curr_sub_category INTO sub_cat_id; UNTIL no_more_sub_categories = 1 END REPEAT; CLOSE curr_sub_category; SELECT advert_count; END // delimiter ; If I remove or comment out the recursive call, the procedure is working. Any idea what I'm missing here? The categories are 2 level deep.

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  • How to merge arraylist element ?

    - by tiendv
    I have a string example = " Can somebody provide an algorithm sample code in your reply ", after token and do some i want on string example i have arraylist like : ArrayList <token > arl = " "Can somebody provide ", "code in your ", "somebody provide an algorith", " in your reply" ) "Can somebody provide ", i know position start and end in string test : star = 1 end = 3 " code in your ", i know position stat = 7 end = 10, "somebody provide an algorith", i know position stat = 7 end = 10, "in your reply" i know position stat = 11 end = 14, we can see,some element in arl overlaping :"Can somebody provide "," code in your ","somebody provide an algorith". The problem here is how can i merge overlaping element to recived arraylist like ArrayList result ="" Can somebody provide an algorithm sample code","" in your reply""; Here my code : but it only merge fist elecment if check is overloaping public ArrayList<TextChunks> finalTextChunks(ArrayList<TextChunks> textchunkswithkeyword) { ArrayList<TextChunks > result = (ArrayList<TextChunks>) textchunkswithkeyword.clone(); //System.out.print(result.size()); int j; for(int i=0;i< result.size() ;i++) { int index = i; if(i+1>=result.size()){ break; } j=i+1; if(result.get(i).checkOverlapingTwoTextchunks(result.get(j))== true) { TextChunks temp = new TextChunks(); temp = handleOverlaping(textchunkswithkeyword.get(i),textchunkswithkeyword.get(j),resultSearchEngine); result.set(i, temp); result.remove(j); i = index; continue; } } return result; } Thanks in avadce

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  • Segmentation Fault

    - by Biranchi
    Hi All, I have the following piece of code for getting the hostname and IP address, #include <stdlib.h> #include <stdio.h> #include <netdb.h> /* This is the header file needed for gethostbyname() */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct hostent *he; if (argc!=2){ printf("Usage: %s <hostname>\n",argv[0]); exit(-1); } if ((he=gethostbyname(argv[1]))==NULL){ printf("gethostbyname() error\n"); exit(-1); } printf("Hostname : %s\n",he->h_name); /* prints the hostname */ printf("IP Address: %s\n",inet_ntoa(*((struct in_addr *)he->h_addr))); /* prints IP address */ } but i am getting a warning and segmentation fault as host.c: In function ‘main’: host.c:24: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’ What is the error in the code ?? Thanks

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  • How to call a method in another class using the arraylist index in java?

    - by Puchatek
    Currently I have two classes. A Classroom class and a School class. public void addTeacherToClassRoom(Classroom myClassRoom, String TeacherName) I would like my method addTeacherToClassRoom to use the Classroom Arraylist index number to setTeacherName e.g. int 0 = maths int 1 = science I would like to setTeacherName "Daniel" in int 1 science. many, thanks public class Classroom { private String classRoomName; private String teacherName; public void setClassRoomName(String newClassRoomName) { classRoomName = newClassRoomName; } public String returnClassRoomName() { return classRoomName; } public void setTeacherName(String newTeacherName) { teacherName = newTeacherName; } public String returnTeacherName() { return teacherName; } } import java.util.ArrayList; public class School { private ArrayList<Classroom> classrooms; private String classRoomName; private String teacherName; public School() { classrooms = new ArrayList<Classroom>(); } public void addClassRoom(Classroom newClassRoom, String theClassRoomName) { classrooms.add(newClassRoom); classRoomName = theClassRoomName; } public void addTeacherToClassRoom(Classroom myClassRoom, String TeacherName) { myClassRoom.setTeacherName(TeacherName); } }

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  • Fixing an SQL where statement that is ugly and confusing

    - by Mike Wills
    I am directly querying the back-end MS SQL Server for a software package. The key field (vehicle number) is defined as alpha though we are entering numeric value in the field. There is only one exception to this, we place an "R" before the number when the vehicle is being retired (which means we sold it or the vehicle is junked). Assuming the users do this right, we should not run into a problem using this method. (Right or wrong isn't the issue here) Fast forward to now. I am trying to query a subset of these vehicle numbers (800 - 899) for some special processing. By doing a range of '800' to '899' we also get 80, 81, etc. If I cast the vehicle number into an INT, I should be able to get the right range. Except that these "R" vehicles are kicking me in the butt now. I have tried where vehicleId not like 'R%' and cast(vehicleId as int) between 800 and 899 however, I get a casting error on one of these "R" vehicles. What does work is where vehicleId not between '800' and '899' and cast(vehicleId as int) between 800 and 899', but I feel there has to be a better way and less confusing way. I have also tried other variations with HAVING and a sub-query all producing a casting error.

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  • Removing and restoring Window borders

    - by Laurence
    I want to remove the window borders of another process in C#; I used RemoveMenu to remove the borders. It almost works but I have 2 problems left: I need to remove the borders twice, the first time the menu bar still exists. I can’t restore the menu’s This is what I already wrote: public void RemoveBorders(IntPtr WindowHandle, bool Remove) { IntPtr MenuHandle = GetMenu(WindowHandle); if (Remove) { int count = GetMenuItemCount(MenuHandle); for (int i = 0; i < count; i++) RemoveMenu(MenuHandle, 0, (0x40 | 0x10)); } else { SetMenu(WindowHandle,MenuHandle); } int WindowStyle = GetWindowLong(WindowHandle, -16); //Redraw DrawMenuBar(WindowHandle); SetWindowLong(WindowHandle, -16, (WindowStyle & ~0x00080000)); SetWindowLong(WindowHandle, -16, (WindowStyle & ~0x00800000 | 0x00400000)); } Can someone show me what I did wrong? I already tried to save the MenuHandle and restore it later, but that doesn't work.

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  • Detect modification of variable at runtime in C/C++

    - by YuppieNetworking
    Hello, I am developing a library in C++ where users/programmer will extend a class BaseClass that has a method initArray. This method should be implemented by the user/programmer and it should normally initialize all elements of the array m_arr. Here is a snipplet, modified to this example: class BaseClass { public: BaseClass(int n) { m_arr = new double[n]; size = n; }; virtual ~BaseClass(); int size; double* m_arr; virtual int initArray(); }; Sometimes, the user/programmer implements a initArray that does not initialize some elements of m_arr. What I would like is to create a function in my library that checks if initArray did initialize all elements of m_arr. This function should be called by a sanity-check rutine at runtime. My question: is it possible to detect changes on this array? I can only think of initializing the array with some invalid values (like NaN or Inf), call initArray and check that all values have changed. Thanks for your ideas, David

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  • returning a pointed to an object within a std::vector

    - by memC
    I have a very basic question on returning a reference to an element of a vector . There is a vector vec that stores instances of class Foo. I want to access an element from this vector . ( don't want to use the vector index) . How should I code the method getFoo here? #include<vector> #include<stdio.h> #include<iostream> #include<math.h> using namespace std; class Foo { public: Foo(){}; ~Foo(){}; }; class B { public: vector<Foo> vec; Foo* getFoo(); B(){}; ~B(){}; }; Foo* B::getFoo(){ int i; vec.push_back(Foo()); i = vec.size() - 1; // how to return a pointer to vec[i] ?? return vec.at(i); }; int main(){ B b; b = B(); int i = 0; for (i = 0; i < 5; i ++){ b.getFoo(); } return 0; }

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  • Trying to get focus onto JTextPane after doubleclicking on JList element (Java)

    - by Alex Cheng
    Hi all. Problem: I have the following JList which I add to the textPane, and show it upon the caret moving. However, after double clicking on the Jlist element, the text gets inserted, but the caret is not appearing on the JTextPane. This is the following code: listForSuggestion = new JList(str.toArray()); listForSuggestion.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); listForSuggestion.setSelectedIndex(0); listForSuggestion.setVisibleRowCount(visibleRowCount); listScrollPane = new JScrollPane(listForSuggestion); MouseListener mouseListener = new MouseAdapter() { @Override public void mouseClicked(MouseEvent mouseEvent) { JList theList = (JList) mouseEvent.getSource(); if (mouseEvent.getClickCount() == 2) { int index = theList.locationToIndex(mouseEvent.getPoint()); if (index >= 0) { Object o = theList.getModel().getElementAt(index); //System.out.println("Double-clicked on: " + o.toString()); //Set the double clicked text to appear on textPane String completion = o.toString(); int num= textPane.getCaretPosition(); textPane.select(num, num); textPane.replaceSelection(completion); textPane.setCaretPosition(num + completion.length()); int pos = textPane.getSelectionEnd(); textPane.select(pos, pos); textPane.replaceSelection(""); textPane.setCaretPosition(pos); textPane.moveCaretPosition(pos); } } theList.clearSelection(); Any idea on how to "de-focus" the selection on the Jlist, or make the caret appear on the JTextPane after the text insertion? I'll elaborate more if this is not clear enough. Please help, thanks!

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  • Syntax for finding structs in multisets - C++

    - by Sarah
    I can't seem to figure out the syntax for finding structs in containers. I have a multiset of Event structs. I'm trying to find one of these structs by searching on its key. I get the compiler error commented below. struct Event { public: bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } bool operator > ( const Event & rhs ) const { return ( time > rhs.time ); } bool operator == ( const Event & rhs ) const { return ( time == rhs.time ); } double time; int eventID; int hostID; int s; }; typedef std::multiset< Event, std::less< Event > > EventPQ; EventPQ currentEvents; double oldRecTime = 20.0; EventPQ::iterator ceItr = currentEvents.find( EventPQ::key_type( oldRecTime ) ); // no matching function call I've tried a few permutations to no avail. I thought defining the conditional equality operator was going to be enough.

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  • C Static Function Confusion

    - by Lime
    I am trying to make the s_cord_print function visible in the cord_s.c file only. Currently the function is visible/runnable in main.c even when it is declared static. How do I make the s_cord_print function private to cord_s.c? Thanks! s_cord.c typedef struct s_cord{ int x; int y; struct s_cord (*print)(); } s_cord; void* VOID_THIS; #define $(EL) VOID_THIS=&EL;EL static s_cord s_cord_print(){ struct s_cord *THIS; THIS = VOID_THIS; printf("(%d,%d)\n",THIS->x,THIS->y); return *THIS; } const s_cord s_cord_default = {1,2,s_cord_print}; main.c #include <stdio.h> #include <stdlib.h> #include "s_cord.c" int main(){ s_cord mycord = s_cord_default; mycord.x = 2; mycord.y = 3; $(mycord).print().print(); //static didn't seem to hide the function s_cord_print(); return 0; } ~

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  • upload new file first check if this file exist already in database or not then if not exist save that in database

    - by Hala Qaseam
    I'm trying to create sql database that contains Image Id (int) Imagename (varchar(50)) Image (image) and in aspx write in upload button this code: protected void btnUpload_Click(object sender, EventArgs e) { //Condition to check if the file uploaded or not if (fileuploadImage.HasFile) { //getting length of uploaded file int length = fileuploadImage.PostedFile.ContentLength; //create a byte array to store the binary image data byte[] imgbyte = new byte[length]; //store the currently selected file in memeory HttpPostedFile img = fileuploadImage.PostedFile; //set the binary data img.InputStream.Read(imgbyte, 0, length); string imagename = txtImageName.Text; //use the web.config to store the connection string SqlConnection connection = new SqlConnection(strcon); connection.Open(); SqlCommand cmd = new SqlCommand("INSERT INTO Image (ImageName,Image) VALUES (@imagename,@imagedata)", connection); cmd.Parameters.Add("@imagename", SqlDbType.VarChar, 50).Value = imagename; cmd.Parameters.Add("@imagedata", SqlDbType.Image).Value = imgbyte; int count = cmd.ExecuteNonQuery(); connection.Close(); if (count == 1) { BindGridData(); txtImageName.Text = string.Empty; ScriptManager.RegisterStartupScript(this, this.GetType(), "alertmessage", "javascript:alert('" + imagename + " image inserted successfully')", true); } } } When I'm uploading a new image I need to first check if this image already exists in database and if it doesn't exist save that in database. Please how I can do that?

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  • Same random numbers from instantiated class

    - by user1797202
    I'm learning C# and created a class within my program that holds a random number generator: class RandomNumberGenerator { Random RNG = new Random(); // A bunch of methods that use random numbers are in here } Inside this class are a few methods that use the RNG. Data gets sent here from other parts of the program, gets processed, then gets returned. One of the methods does the following: // Method works something like this int Value1 = RNG.Next(x, y); int Value2 = RNG.Next(x, y); int Value3 = RNG.Next(x, y); The x, y values are to be sent here from another class. So, I have to create an instance of the RandomNumberGenerator within that class so I can call its methods and pass the x and y values to it. class DoStuff { RandomNumberGenerator Randomizer = new RandomNumberGenerator // Here I call a bunch of Randomizer methods that give me values I need } The problem in the above method is that I get the same numbers every time for all three values. I'm not sure if it's because they're so close together and Randomizer's seed value hasn't had time to change or if I'm doing something wrong when I create a new instance of the RandomNumberGenerator class. I've gone through a bunch of answers on here already and typically problems like this are due to people creating many new Random objects when they run methods (thus setting the seed for all of them to the same value), but the only new Random object I create is within the RandomNumberGenerator class. I then instantiate that once within the other class so I can pass it data and use its methods. Why is this happening and how would I fix this?

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  • multiple inheritance

    - by hitech
    when we say "a member declated as protected is accessible to any class imediately derived from it" what does this mean. in the follwing example get_number function can be accessible by the result class , as per the statement it sould only be accessile to test class. class student { protected: int roll_number; public: void get_number(int){ cout<< "hello"; } void put_number(void) {cout<< "hello"; } }; class test : public student { protected : float sub1; float sub2; public: void get_marks(float, float) {cout<< "hello"; roll_number = 10; } void put_marks(void) {cout<< "hello"; cout << "roll_number = " << roll_number ; } }; class result :public test { float total; public: void display(){cout<< "hello"; roll_number = 10; } }; int main() { result student; student.get_marks(2.2, 2.2); student.put_marks(); return 0; } i changed the code as per the first statement the protected variable roll_number not be accessible upto the result class ?

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