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• BAM design pointers

  - by Kavitha Srinivasan

  In working recently with a large Oracle customer on SOA and BAM, I discovered that some BAM best practices are not quite well known as I had always assumed ! There is a doc bug out to formally incorporate those learnings but here are a few notes..  EMS-DO parity When using EMS (Enterprise Message Source) as a BAM feed, the best practice is to use one EMS to write to one Data Object. There is a possibility of collisions and duplicates when multiple EMS write to the same row of a DO at the same time. This customer had 17 EMS writing to one DO at the same time. Every sensor in their BPEL process writes to one topic but the Topic was read by 1 EMS corresponding to one sensor. They then used XSL within BAM to transform the payload into the BAM DO format. And hence for a given BPEL instance, 17 sensors fired, populated 1 JMS topic, was consumed by 17 EMS which in turn wrote to 1 DataObject.(You can image what would happen for later versions of the application that needs to send more information to BAM !).  We modified their design to use one Master XSL based on sensorname for all sensors relating to a DO- say Data Object 'Orders' and were able to thus reduce the 17 EMS to 1 with a master XSL. For those of you wondering about how squeaky clean this design is, you are right ! This is indeed not squeaky clean and that brings us to yet another 'inferred' best practice. (I try very hard not to state the obvious in my blogs with the hope that everytime I blog, it is very useful but this one is an exception.) Transformations and Calculations It is optimal to do transformations within an engine like BPEL. Not only does this provide modelling ease with a nice GUI XSL mapper in JDeveloper, the XSL engine in BPEL is quite efficient at runtime as well. And so, doing XSL transformations in BAM is not quite prudent.  The same is true for any non-trivial calculations as well. It is best to do all transformations,calcuations and sanitize the data in a BPEL or like layer and then send this to BAM (via JMS, WS etc.) This then delegates simply the function of report rendering and mechanics of real-time reporting to the Oracle BAM reporting tool which it is most suited to do. All nulls are not created equal Here is yet another possibly known fact but reiterated here. For an EMS with an Upsert operation: a) If Empty tags or tags with no value are sent like <Tag1/> or <Tag1></Tag1>, the DO will be overwritten with --null-- b) If Empty tags are suppressed ie not generated at all, the corresponding DO field will NOT be overwritten. The field will have whatever value existed previously.  For an EMS with an Insert operation, both tags with an empty value and no tags result in –null-- being written to the DO. Hope this helps .. Happy 4th!

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• Pointers to implementing a taxonomy system?

  - by petsagouris

  I am taking part in the development of a PHP CMS (yeah I know you are like, meeh). It is currently using simple tags for tagging content. What I want to do is push the whole thing to using Taxonomy but I am not sure on what to pay attention to, or how to go about structuring the whole vocabularies/terms. I'd love to be able to keep the user interaction close to that of the current simple tags and at the same time allow for more advanced usage by power users. The Drupal and the Wordpress taxonomy systems are being reviewed at the moment and they provide valuable resources. Nevertheless, it could be that someone has some simpler and more appropriate thoughts on this matter.

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• Search Engine Optimization Pointers That Would Make Your Website the Most Attractive Online

  There has been much talk around about how the perfect web site should look like. Let us now see how brilliant search engine optimization tips can overcome all your challenges and assist your best site to become the finest website available out there today.

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• C++ difference between "char *" and "char * = new char[]"

  - by nashmaniac

  So, if I want to declare an array of characters I can go this way char a[2]; char * a ; char * a = new char[2]; Ignoring the first declaration, the other two use pointers. As far as I know the third declaration is stored in heap and is freed using the delete operator . does the second declaration also hold the array in heap ? Does it mean that if something is stored in heap and not freed can be used anywhere in a file like a variable with file linkage ? I tried both third and second declaration in one function and then using the variable in another but it didn't work, why ? Are there any other differences between the second and third declarations ?

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• Should *'s go next to the type or the variable name? [closed]

  - by derekerdmann

  Possible Duplicate: int* i; or int *i; or int * i; When working in C or C++, how should pointers be declared? Like this: char* derp; or this: char *derp; I typically use the first method, because the variable is a character pointer, but I know that it can create confusion when declaring multiple variables at once: char* herp, derp; herp becomes a character pointer, while derp is just a character. I know it often comes down to coding style, but which one is "better?" Should I sacrifice clarity to eliminate potential confusion?

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• Lvalue required error [migrated]

  - by ankur.trapasiya

  While working with pointers i wrote the following code, int main() { int a[]={10,20,30,40,50}; int i; for(i=0;i<5;i++) { printf("\n%d",*a); a++; } return 0; } Now as per my understanding array name itself is an address in c and the pointer arithmetic done is here is correct as per my knowledge. But when i try to run the code it is giving me "Lvalue Required" error. So what is the exact reason for occuring Lvalue required error because before this also i have come across situations where this error is there. Secondly why the arithmetic on the pointer is not legal here in this case?

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• How to @synthesize a C-Style array of pointers?

  - by Peter Hajas

  I have a property defined in a class like so: @interface myClass UIImageView *drawImage[4]; ... @property (nonatomic, retain) UIImageView **drawImage; ... @synthesize drawImage; // This fails to compile I have found similar questions on StackOverflow and elsewhere, but none that really address this issue. What is the most Objective-C kosher way to do this?

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• Pointers, am I doing them correctly? Objective-c/cocoa

  - by Chris

  I have this in my @interface struct track currentTrack; struct track previousTrack; int anInt; Since these are not objects, I do not have to have them like int* anInt right? And if setting non-object values like ints, boolean, etc, I do not have to release the old value right (assuming non-GC environment)? The struct contains objects: typedef struct track { NSString* theId; NSString* title; } *track; Am I doing that correctly? Lastly, I access the struct like this: [currentTrack.title ...]; currentTrack.theId = @"asdf"; //LINE 1 I'm also manually managing the memory (from a setter) for the struct like this: [currentTrack.title autorelease]; currentTrack.title = [newTitle retain]; If I'm understanding the garbage collection correctly, I should be able to ditch that and just set it like LINE 1 (above)? Also with garbage collection, I don't need a dealloc method right? If I use garbage collection does this mean it only runs on OS 10.5+? And any other thing I should know before I switch to garbage collected code? Sorry there are so many questions. Very new to objective-c and desktop programming. Thanks

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• Using `<List>` when dealing with pointers in C#.

  - by Gorchestopher H

  How can I add an item to a list if that item is essentially a pointer and avoid changing every item in my list to the newest instance of that item? Here's what I mean: I am doing image processing, and there is a chance that I will need to deal with images that come in faster than I can process (for a short period of time). After this "burst" of images I will rely on the fact that I can process faster than the average image rate, and will "catch-up" eventually. So, what I want to do is put my images into a <List> when I acquire them, then if my processing thread isn't busy, I can take an image from that list and hand it over. My issue is that I am worried that since I am adding the image "Image1" to the list, then filling "Image1" with a new image (during the next image acquisition) I will be replacing the image stored in the list with the new image as well (as the image variable is actually just a pointer). So, my code looks a little like this: while (!exitcondition) { if(ImageAvailabe()) { Image1 = AcquireImage(); ImgList.Add(Image1); } if(ImgList.Count 0) { ProcessEngine.NewImage(ImgList[0]); ImgList.RemoveAt(0); } } Given the above, how can I ensure that: - I don't replace all items in the list every time Image1 is modified. - I don't need to pre-declare a number of images in order to do this kind of processing. - I don't create a memory devouring monster. Any advice is greatly appreciated.

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• how to Clean up(destructor) a dynamic Array of pointers??

  - by Ahmed Sharara

  Is that Destructor is enough or do I have to iterate to delete the new nodes?? #include "stdafx.h" #include<iostream> using namespace std; struct node{ int row; int col; int value; node* next_in_row; node* next_in_col; }; class MultiLinkedListSparseArray { private: char *logfile; node** rowPtr; node** colPtr; // used in constructor node* find_node(node* out); node* ins_node(node* ins,int col); node* in_node(node* ins,node* z); node* get(node* in,int row,int col); bool exist(node* so,int row,int col); //add anything you need public: MultiLinkedListSparseArray(int rows, int cols); ~MultiLinkedListSparseArray(); void setCell(int row, int col, int value); int getCell(int row, int col); void display(); void log(char *s); void dump(); }; MultiLinkedListSparseArray::MultiLinkedListSparseArray(int rows,int cols){ rowPtr=new node* [rows+1]; colPtr=new node* [cols+1]; for(int n=0;n<=rows;n++) rowPtr[n]=NULL; for(int i=0;i<=cols;i++) colPtr[i]=NULL; } MultiLinkedListSparseArray::~MultiLinkedListSparseArray(){ // is that destructor enough?? cout<<"array is deleted"<<endl; delete [] rowPtr; delete [] colPtr; }

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• Dereferencing deleted pointers always result in an Access Violation ??

  - by m3rLinEz

  I have a very simple C++ code here: char *s = new char[100]; strcpy(s, "HELLO"); delete [] s; int n = strlen(s); If I run this code from Visual C++ 2008 by pressing F5 (Start Debugging,) this always result in crash (Access Violation.) However, starting this executable outside the IDE, or using the IDE's Ctrl+F5 (Start without Debugging) doesn't result in any crash. What could be the difference? I also want to know if it's possible to stably reproduce the Access Violation crash caused from accessing deleted area? Is this kind of crash rare in real-life?

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• C++ vector of strings, pointers to functions, and the resulting frustration.

  - by Kyle

  So I am a first year computer science student, for on of my final projects, I need to write a program that takes a vector of strings, and applies various functions to these. Unfortunately, I am really confused on how to use pointer to pass the vector from function to function. Below is some sample code to give an idea of what I am talking about. I also get an error message when I try to deference any pointer. thanks. #include <iostream> #include <cstdlib> #include <vector> #include <string> using namespace std; vector<string>::pointer function_1(vector<string>::pointer ptr); void function_2(vector<string>::pointer ptr); int main() { vector<string>::pointer ptr; vector<string> svector; ptr = &svector[0]; function_1(ptr); function_2(ptr); } vector<string>::pointer function_1(vector<string>::pointer ptr) { string line; for(int i = 0; i < 10; i++) { cout << "enter some input ! \n"; // i need to be able to pass a reference of the vector getline(cin, line); // through various functions, and have the results *ptr.pushback(line); // reflectedin main(). But I cannot use member functions } // of vector with a deferenced pointer. return(ptr); } void function_2(vector<string>::pointer ptr) { for(int i = 0; i < 10; i++) { cout << *ptr[i] << endl; } }

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• Pointers to a typed variable in C#: Interfase, Generic, object or Class? (Boxing/Unboxing)

  - by PaulG

  First of all, I apologize if this has been asked a thousand times. I read my C# book, I googled it, but I can't seem to find the answer I am looking for, or I am missing the point big time. I am very confused with the whole boxing/unboxing issue. Say I have fields of different classes, all returning typed variables (e.g. 'double') and I would like to have a variable point to any of these fields. In plain old C I would do something like: double * newVar; newVar = &oldVar; newVar = &anotherVar; ... In C#, it seems I could do an interfase, but would require that all fields be properties and named the same. Breaks apart when one of the properties doesn't have the same name or is not a property. I could also create a generic class returning double, but seems a bit absurd to create a class to represent a 'double', when a 'double' class already exists. If I am not mistaken, it doesn't even need to be generic, could be a simple class returning double. I could create an object and box the typed variable to the newly created object, but then I would have to cast every time I use it. Of course, I always have the unsafe option... but afraid of getting to unknown memory space, divide by zero and bring an end to this world. None of these seem to be the same as the old simple 'double * variable'. Am I missing something here?

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• Incorrect data when passing pointer a list of pointers to a function. (C++)

  - by Phil Elm

  I'm writing code for combining data received over multiple sources. When the objects received (I'll call them MyPacket for now), they are stored in a standard list. However, whenever I reference the payload size of a partial MyPacket, the value shows up as 1 instead of the intended size. Here's the function code: MyPacket* CombinePackets(std::list<MyPacket*>* packets, uint8* current_packet){ uint32 total_payload_size = 0; if(packets->size() <= 0) return NULL; //For now. std::list<MyPacket*>::iterator it = packets->begin(); //Some minor code here, not relevant to the problem. for(uint8 index = 0; index < packets->size(); index++){ //(*it)->GetPayloadSize() returns 1 when it should show 1024. I've tried directly accessing the variable and more, but I just can't get it to work. total_payload_size += (*it)->GetPayloadSize(); cout << "Adding to total payload size value: " << (*it)->GetPayloadSize() << endl; std::advance(it,1); } MyPacket* packet = new MyPacket(); //Byte is just a typedef'd unsigned char. packet->payload = (byte) calloc(total_payload_size, sizeof(byte)); packet->payload_size = total_payload_size; it = packets->begin(); //Go back to the beginning again. uint32 big_payload_index = 0; for(uint8 index = 0; index < packets->size(); index++){ if(current_packet != NULL) *current_packet = index; for(uint32 payload_index = 0; payload_index < (*it)->GetPayloadSize(); payload_index++){ packet->payload[big_payload_index] = (*it)->payload[payload_index]; big_payload_index++; } std::advance(it,1); } return packet; } //Calling code std::list<MyPacket*> received = std::list<MyPacket*>(); //The code that fills it is here. std::list<MyPacket*>::iterator it = received.begin(); cout << (*it)->GetPayloadSize() << endl; // Outputs 1024 correctly! MyPacket* final = CombinePackets(&received,NULL); cout << final->GetPayloadSize() << endl; //Outputs 181, which happens to be the number of elements in the received list. So, as you can see above, when I reference (*it)-GetPayloadSize(), it returns 1 instead of the intended 1024. Can anyone see the problem and if so, do you have an idea on how to fix this? I've spent 4 hours searching and trying new solutions, but they all keep returning 1... EDIT:

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• what is function pointers in vbscript?

  - by Anil

  can some one clarify what is function pointers in vb script

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• Using std::bad_alloc for C pointers

  - by otibom

  I'm using a library written in C in a C++ project. I'd like to use C++ exceptions to handle C errors. In particular, it would be nice to have an exception thrown if an allocation fails. I can do this in constructors of classes which hold C-style pointers to C structs : if (c_object == NULL) throw std::bad_alloc(); But if the class is responsible for several C objects they are no ways of free-ing all already allocated pointers since the destructor isn't called. I have a feeling I could use smart-pointers, but I don't have much experience with them. What's more, I have to have access to the original C pointers to use the C api properly. Is there an elegant solution to this ?

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• Pointers and collection of pointers in C++. How to properly delete.

  - by Julen

  Hello, This is a newbe question but I have alwasy doubts with pointers in C++. This is the situation. I have a class A which as a collection (a vector actually) of pointers of class B. This same class A has another collection of pointers to class C. Finally the objects of class B have also a collection to pointers to class C which point to the same instances the class A points to. My question is, if I delete a member of class-C-type pointer in class B, what happens to the pointer in class A that points to the deleted instance of class C? How this situation has to be treated? Thanks a lot in advance! Julen.

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• uninitialized local variable

  - by blitzeus

  This code compiles and runs though gives a Microsoft compiler error that I cant fix warning C4700: uninitialized local variable 'ptr4D' used. This is in the last line of the code, I think #include <iostream> using namespace std; const int DIM0 = 2, DIM1 = 3, DIM2 = 4, DIM3 = 5; void TestDeclar(); int main(){ TestDeclar(); cout << "Done!\n"; return 0; } void TestDeclar(){ //24 - array of 5 floats float xa[DIM3], xb[DIM3], xc[DIM3], xd[DIM3], xe[DIM3], xf[DIM3]; float xg[DIM3], xh[DIM3], xi[DIM3], xj[DIM3], xk[DIM3], xl[DIM3]; float xm[DIM3], xn[DIM3], xo[DIM3], xp[DIM3], xq[DIM3], xr[DIM3]; float xs[DIM3], xt[DIM3], xu[DIM3], xv[DIM3], xw[DIM3], xx[DIM3]; //6 - array of 4 pointers to floats float *ya[DIM2] = {xa, xb, xc, xd}, *yb[DIM2] = {xe, xf, xg, xh}; float *yc[DIM2] = {xi, xj, xk, xl}, *yd[DIM2] = {xm, xn, xo, xp}; float *ye[DIM2] = {xq, xr, xs, xt}, *yf[DIM2] = {xu, xv, xw, xx}; //2 - array of 3 pointers to pointers of floats float **za[DIM1] = {ya, yb, yc}; float **zb[DIM1] = {yd, ye, yf}; //array of 2 pointers to pointers to pointers of floats float ***ptr4D[DIM0] = {za, zb}; cout << &***ptr4D[DIM0] << '\n'; }

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• c incompatible types in assignment, problem with pointers?

  - by Fantastic Fourier

  Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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• Indices instead of pointers in STL containers?

  - by zvrba

  Due to specific requirements [*], I need a singly-linked list implementation that uses integer indices instead of pointers to link nodes. The indices are always interpreted with respect to a vector containing the list nodes. I thought I might achieve this by defining my own allocator, but looking into the gcc's implementation of , they explicitly use pointers for the link fields in the list nodes (i.e., they do not use the pointer type provided by the allocator): struct _List_node_base { _List_node_base* _M_next; ///< Self-explanatory _List_node_base* _M_prev; ///< Self-explanatory ... } (For this purpose, the allocator interface is also deficient in that it does not define a dereference function; "dereferencing" an integer index always needs a pointer to the underlying storage.) Do you know a library of STL-like data structures (i am mostly in need of singly- and doubly-linked list) that use indices (wrt. a base vector) instead of pointers to link nodes? [*] Saving space: the lists will contain many 32-bit integers. With two pointers per node (STL list is doubly-linked), the overhead is 200%, or 400% on 64-bit platform, not counting the overhead of the default allocator.

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• C++ String pointers

  - by gnm

  In my previous app I had an object like this: class myType { public: int a; string b; } It had a lot of instances scattered everywhere and passed around to nearly every function. The app was slow. Profiling said that 95% of time is eaten by the string allocator function. I know how to work with the object above, but not how to work with string pointers. class myType { public: int a; string* b; } They told me to use pointers as above. How much faster is it with a string pointer? What is copied when I copy the object? How to the following using the class with the pointer: Access the string value Modify the string value without modifying the one in the object (copy?) General things that change if I use string pointers?

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• C++ Vector of pointers

  - by xbonez

  For my latest CS homework, I am required to create a class called Movie which holds title, director, year, rating, actors etc. Then, I am required to read a file which contains a list of this info and store it in a vector of pointers to Movies. I am not sure what the last line means. Does it mean, I read the file, create multiple Movie objects. Then make a vector of pointers where each element (pointer) points to one of those Movie objects? Do I just make two vectors - one of pointers and one of Movies and make a one-to-one mapping of the two vectors?

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• Mouse pointer strange problem...

  - by Paska

  Hi all, i have last ubuntu installed (10.10), but from an year and thousand updates, video drivers updates, an hundreds of tricks, the mouse pointer is showed like an UGLY square... These are the screenshots: First Second I have no idea what to do to solve this problem. Anyone of you have an idea to solve it? Edit: this problem was encountered from 8.10+! Edit 2, Video card specifications: paska@ubuntu:~$ hwinfo --gfxcard 35: PCI 100.0: 0300 VGA compatible controller (VGA) [Created at pci.318] UDI: /org/freedesktop/Hal/devices/pci_1106_3230 Unique ID: VCu0.QX54AGQKWeE Parent ID: vSkL.CP+qXDDqow8 SysFS ID: /devices/pci0000:00/0000:00:01.0/0000:01:00.0 SysFS BusID: 0000:01:00.0 Hardware Class: graphics card Model: "VIA K8M890CE/K8N890CE [Chrome 9]" Vendor: pci 0x1106 "VIA Technologies, Inc." Device: pci 0x3230 "K8M890CE/K8N890CE [Chrome 9]" SubVendor: pci 0x1043 "ASUSTeK Computer Inc." SubDevice: pci 0x81b5 Revision: 0x11 Memory Range: 0xd0000000-0xdfffffff (rw,prefetchable) Memory Range: 0xfa000000-0xfaffffff (rw,non-prefetchable) Memory Range: 0xfbcf0000-0xfbcfffff (ro,prefetchable,disabled) IRQ: 16 (10026 events) I/O Ports: 0x3c0-0x3df (rw) Module Alias: "pci:v00001106d00003230sv00001043sd000081B5bc03sc00i00" Driver Info #0: Driver Status: viafb is not active Driver Activation Cmd: "modprobe viafb" Config Status: cfg=new, avail=yes, need=no, active=unknown Attached to: #17 (PCI bridge) Primary display adapter: #35 paska@ubuntu:~$ thanks, A

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• Pointer initialization doubt

  - by Jestin Joy

  We could initialize a character pointer like this in C. char *c="test"; Where c points to the first character(t). But when I gave code like below. It gives segmentation fault. #include<stdio.h> #include<stdlib.h> main() { int *i; *i=0; printf("%d",*i); } But when I give #include<stdio.h> #include<stdlib.h> main() { int *i; i=(int *)malloc(2); *i=0; printf("%d",*i); } It works( gives output 0). Also when I give malloc(0), It also works( gives output 0). Please tell what is happening

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• Allocating memory inside a function and returning it back

  - by user2651062

  I want to pass a pointer to my function and allocate the memory to which this pointer points. I've read in other posts that I should pass a double pointer to this function and I did so, but I keep getting segmentation fault: #include <iostream> #include <stdlib.h> using namespace std; void allocate(unsigned char** t) { *t=(unsigned char*)malloc(3*sizeof(unsigned char)); if(*t == NULL) cout<<"Allcoation failed"<<endl; else for(int m=0;m<3;m++) *(t[m])=0; } int main() { unsigned char* t; allocate(&t); cout<<t[0]<<" "<<t[1]<<endl; return 0; } the result is always this: Segmentation fault (core dumped) I don't think that there's anything missing from this code. What could be wrong?

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