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In this era of digitalization, customers need solution and also get solution with a few clicks. So it is important for a Tour operator to have a good travel software solution to manage and enhance their business. It will help them to target more customers and manage them properly. When the customer needs their preference so it will help Tour Operator to customize as per them.For an inbound/ outbound /DMC operator, QuadLabs offers an online solution through which they can consolidate, distribute and manage their inventory, bookings and business processes. Through a single online platform a tour operator can manage their holiday/ tour packages, sales channels, along with their own staff & branches.Using our system, tour operator can offer multiple hotels under same holiday package with different allocations and pricing on different dates. This feature helps the customers to avail the hotel as per his comfort ability and budget.Once the traveler has completed his journey then tour operator can send feedback request form for customer feedback which help tour operator to improve his services and packages. As a result it leads to customer satisfaction.QuadLabs system manages the profile of customers & also captures the booking history which can also be view by the customers using their login credentials from tour operator’s website.

In this era of digitization,customers need solution and also get solution with a few clicks. So it is important for a Tour operator to have a good travel software solution to manage & enhance their business. It will help them to target more customers and manage them properly. When the customer needs their preference so it will help Tour Operator to customize as per them.For an inbound/ outbound/ DMC operator,QuadLabs offers an online solution through which they can consolidate, distribute and manage their inventory, bookings and business processes. Through a single online platform a tour operator can manage their holiday/tour packages,sales channels, along with their own staff and branches.Using our system, tour operator can offer multiple hotels under same holiday package with different allocations and pricing on different dates. This feature helps the customers to avail the hotel as per his comfortability and budget.Once the traveler has completed his journey then tour operator can send feedback request form for customer feedback which help tour operator to improve his services and packages. As a result it leads to customer satisfaction.QuadLabs system manages the profile of customers & also captures the booking history which can also be view by the customers using their login credentials from tour operator’s website.

I believe you’re asking how C++’s std::vector works its magic: As long as you have enough memory, you can push_back() on a std::vector, and it will resize itself as needed.How does it manage that, especially considering that C++ doesn’t provide a way to grow an allocation made with new[]?¹First item: std::vector is not built around C-style statically sized arrays such as a[100]. It uses dynamically allocated memory that looks more like what you’d get from new char[]. And the char[] detail there is important, and I’ll get to it later.A std::vector tracks at least three details internally:A pointer to the space it has allocated.The total number of active elements. This is reflected in std::vector<T>::size().The total number of elements it has allocated space for. This is reflected in std::vector<T>::capacity().I will refer to the quantities in #2 and #3 as size and capacity, respectively. This matches how C++ defines the terms for its containers.What’s the difference between the two?A std::vector allocates memory in chunks larger than one element. You might have a std::vector with only one valid element. The std::vector may have allocated room for several elements.So, size represents the number of valid elements, while capacity represents how large size can become before std::vector has to allocate memory.When you execute push_back(item), std::vector looks to see whether size < capacity. If it is, then it knows it can create the new valid element within the storage it has allocated, and increase size by 1.If size == capacity, then it needs to increase capacity. Now we’re at the crux of your question. How does that happen?It happens in much the same way a family might move from a smaller house to a bigger house:Buy a bigger house first.Move everything from the smaller house to the bigger house.File a change of address card and inform everyone of the new address.Sell the smaller house.That might seem glib, but it’s actually a pretty reasonable model of what happens.When size is about to exceed capacity, std::vector computes a new capacity that is a geometric ratio² larger than the previous capacity. IIRC, GNU’s libstdc++ doubles the capacity, and MSVC multiplies the capacity by 1.5.Once it’s done that, it then:Allocates a new chunk of memory with the newly computed capacity.Copies or moves elements from the old storage to the new storage.Updates the internal pointer to the new storage.Frees the old allocated storage.If you look at the “move into a bigger house” list and compare it to what std::vector actually does, you can see how the two relate.So what is this with copies or moves? Prior to C++11, this would have just said “copies.”When you move to a new house, you physically move furniture, books, clothes, etc. from one place to another. Inside a computer, you don’t typically move data. You copy it. And that remains true even if the instruction that does the operation is named “move.”For example, if you write MOV AX, BX in 8086 assembly language, you have actually copied a value.Now, when you have complex data structures, it turns out copying isn’t cheap.C++11 adds a new feature called move semantics. That allows you to move a value from one object to another cheaply. This allows one object to steal already-allocated resources from another. For objects that support this action,³ std::vector will move values rather than copy them. (And, technically speaking, that move is still built out of steps that copy details. The idea is: if we can copy a pointer rather than copying what it points to, that's often a win. Not all moves work that way, but many do.)I won’t dig further into the details here. Just know that when std::vector allocates new storage, it arranges for the data it currently holds to either get copied or moved to the new storage.I mentioned new char[] is important. That’s a slight lie, but only slightly. What’s important is that std::vector can allocate uninitialized memory. Our goal is to separate allocating memory from initializing memory.This gets into some subtleties of the language, and how C++ handles object allocation and construction. The tl;dr: std::vector wants to take over responsibility for when objects actually get constructed.By default, C++’s new operator allocates memory and initializes it in one form or another.That is, when you say something like…mytype* ptr = new mytype[size]; C++ will allocate memory large enough to hold size objects of mytype, and it will default initialize them. If mytype is a class type with expensive default initialization, then this could be fairly expensive. It could also be a complete waste of time if we’re going to replace all of those elements with something useful later.So, instead, std::vector could do something like new char[sizeof(mytype)*size].⁴ This allocates enough space for size instances of mytype.But does new[] initialize them?In C++, the default initialization for char does nothing. So, new char[] technically default initializes the chars, but there’s nothing to do. It just hands you bulk, uninitialized memory. Thus, new char[] provides a reasonable way to allocate bulk memory without any initialization overhead.Is there a better way?There is another standard way that’s more straightforward, and is what libstdc++ uses: ::operator new().[1] This allocates bulk, uninitialized memory with the specified size and alignment. It’s very similar to C’s malloc(), actually, and is designed that way on purpose. The :: indicates that we’re asking for the global function that is not a member of any class or namespace.The new operator calls the function operator new() only to allocate storage. The new operator then initializes the object in the allocated storage. When we call operator new() directly, we skip the initialization step. We don’t need any special guarantees about what default initialization means for a particular type.So, when do we initialize the memory?The std::vector allocates additional space to increase the vector’s capacity, rather than its size. As I mentioned before, size tracks the number of active, initialized elements, while capacity tracks how much memory we’ve allocated, and capacity >= size.After allocating a new, uninitialized chunk of memory, std::vector will migrate elements out of the old storage and into the new storage. This initializes the first size elements of the new storage. The remaining portion—after size, up to capacity—remains uninitialized.As you push additional elements into std::vector, you increase its size. As you fill the remaining capacity (i.e. size grows toward capacity), push_back() initializes each subsequent element. And, of course, if you try to push size > capacity, std::vector will increase the capacity before proceeding.So, how do we initialize the memory?The std::vector uses placement-new to initialize each object in the newly allocated space. This is true both when it migrates objects from the old storage, as well as when you push new objects into the vector. Placement-new provides initialization without performing allocation. It provides the piece we skipped above by calling ::operator new() (or, new char[], or some other suitable allocation function).In other words, operator new() and placement-new provide the two separate pieces of functionality that new ordinarily provides as a single package.And what about de-initializing the memory? That is, what happens when the vector shrinks?Popping an item off the back of a std::vector decreases its size. Whenever we reduce the vector’s size, std::vector destroys the objects that were removed by explicitly invoking the destructor for each. Once the objects are destroyed, their memory is now considered uninitialized.So what would all this look like as code?Here’s a bit of pseudo-code for a naive implementation of vector<T>::push_back() that assumes we have data, size, and capacity members in our vector. Note that I left std:: off, as this is a pseudo-code implementation, and not a full-fat standard-compliant implementation.template <typename T> void vector<T>::push_back(const T& item) {  if (size == capacity) {  std::size_t new_capacity = capacity * 2;  T* new_data =  static_cast<T*>(new char[sizeof(T)*new_capacity]);    // First, copy all the objects.  for (size_t i = 0; i != size; i++) {  // Use placement new to copy each object.  new(&new_data[i]) T(data[i]);  }    // If there were no issues, delete the originals.  // Do this in reverse order of allocation.  for (size_t i = size; i != 0; --i) {  // Explicitly call the destructor on each of  // the old copies we're about to abandon.  data[i - 1].~T();  }    T* old_data = data; // Remember our old pointer.  data = new_data; // Update to the new pointer.   // Now we can delete our previous storage. The  // cast to char* ensures delete[] treats this as  // bulk memory with no actual destructors. We  // already called the destructors for all of the  // active elements above, after copying them.  delete[] static_cast<char*>(old_data);  } // if (size == capacity)    // Construct the new item in place and increase our size.  new(&data[size++]) T(item); }  There’s a lot going on there, in just a few lines of code.I think I got many of the corner cases correct, but if I flubbed something, please let me know in the comments. While I called this pseudo-code, it actually should be reasonably correct C++. It does not account for all corner cases, though. And in real code, you would probably have a separate helper function for growing the vector.One detail I did not explicitly address is exception safety. You need some additional code in there to ensure we don’t have a memory leak if an exception occurs. And while I did separate copying from destroying, there’s still additional work required to handle properly destroying the partially-initialized new_data in case one of the copy operations throws an exception.Big note: This pseudo-code represents vector differently than GCC’s libstdc++’s std::vector. Rather than storing size and capacity as integers, libstdc++ instead keeps three pointers:One to the allocated storage. Same idea as mine above.A pointer to data + size.A pointer to data + capacity.You can still compute all the same expressions I computed. There are cases, though, where it’s more efficient to store these derived quantities. For example, std::vector<T>::end() can return the “pointer to data + size” directly with no computation.Addendum: I describe in the comments below how [math]O(1)[/math] amortized cost works.Also, I have ignored one layer of abstraction here: Allocator. The std::vector implementation doesn't necessarily call allocation functions directly. You can provide it an alternate, custom allocator. It defaults to std::allocator;[2] however, as Josh's comment below suggests, that doesn't necessarily constrain the implementation to the simple API guaranteed by the standard.Addendum 2: I have ignored other mechanisms std::vector provides, such as resize(), emplace_back(), insert(), and delete() which also can change the size of a vector. I’ve also extended my allocator section to discuss operator new(), as suggested in the comments.¹C provides realloc for reallocating memory allocated by malloc. It performs a bit-image copy to the newly allocated space if it cannot extend the current allocation as requested in-place. C++’s new[] and delete[] don’t have an equivalent.²You could build a valid vector implementation with a linear increase here, rather than geometric. std::vector, however, implicitly requires a geometric increase here, due to its [math]O(1)[/math] amortized cost requirement for push_back(). That’s another topic for another day.³…without throwing exceptions…⁴There are corner cases, such as when mytype has more restrictive alignment than what new guarantees as its minimum alignment.Footnotes[1] operator new, operator new[][2] std::allocator - cppreference.com