作者: _Redstone_c_

struct fenwick_tree_2d_t { lli n, m; array2d_t tre; fenwick_tree_2d_t(lli n, lli m) : n(n), m(m), tre(n + 1, m + 1, 0) { } lli lowbit(lli x) { return x & -x; } void build(lli** arr) { for (lli i = 1; i <= n; ++i) for (lli j = 1; j &

template struct array2d_t { lli n, m; vector data; array2d_t(lli n, lli m) : n(n), m(m), data(n* m) { } array2d_t(lli n, lli m, lli v) : n(n), m(m) , data(n* m, v) { } decltype(auto) operator[](tuple ind) {

struct group_t { struct edge_t { lli u; lli v; lli w; lli nxt; }; lli n; vector head; vector edge; group_t(lli n) : n(n), head(n + 1, -1), edge(1) { } void add_edge(lli u, lli v, lli w) { edge.push_back({ u, v , w, head[u] });

struct mat { lli n, m; vector vec; mat(lli n, lli m) : n(n), m(m) { vec.resize(n * m); } lli& at(lli i, lli j) { return vec[(i – 1) * m + j – 1]; } lli at(lli i, lli j) const { return vec[(i – 1) * m + j – 1]; } void zero(lli x = 0) {

C/C++ Reference Manual graph LR Fundamental[Basic type std::is_fundamental] Void[void std::is_void] NullPointer[std::nullptr_t std::is_null_pointer] Arithmetic[arithmetic type std::is_arithmetic] FloatingPoint[floating point type std::is_floati

As we all know, struct in C++ comes from the historical legacy of the C language. Except that the default scope is public, it is no different from class. In theory, it can be mixed. Here we use the standard library and engineering practices such as Unreal to summarize the selection of struct and class keywords. If the type contains non-public member variables, class should be selected. If the type contains virtual functions, class should be selected. If the type can be aggregate-initialized, struct should be considered. If the type's construction, destruction and assignment functions are = default; implementation

This article was generated entirely by ChatGPT. std::function and std::any adopt the implementation method of constructing new objects and exchanging them, which also has some other advantages and benefits. For example, this implementation can avoid the assignment operator (operator=) throwing exceptions, thus ensuring the exception safety of assignment operations. For example, if std::function and std::any implement assignment by directly calling the assignment operation, then if an exception is thrown during the assignment operation, the state of the object may change, resulting in abnormal termination of the program. The implementation method of constructing new objects and exchanging them can avoid exceptions thrown during assignment operations.

First, here is an excerpt from the description of this part on cppreference. Variables declared at block scope with the static or thread_local specifier have static or thread storage duration, but are not initialized until control first passes through their declaration. In all subsequent calls, the declaration is skipped. If initialization throws an exception, the variable is not considered initialized, and initialization is attempted again the next time control passes through the declaration. The behavior is undefined if initialization recursively enters the block of the variable being initialized. The initialization of static local variables inside a function is performed when the function is first called, and will not be initialized in subsequent calls. In a multi-threaded environment, static layout can still be guaranteed.

Class life cycle and common operator tracker struct FTracker { FTracker() { std::cout << "FTracker()" << std::endl; } FTracker(const FTracker&) { std::cout << "FTracker( const FTracker&)" << std::endl; } FTracker(FTracker&&am

Function signature reference documentation: new – delete Versioned replaceable allocation functions and replaceable deallocation functions are implicitly declared in each translation unit even if the standard library header file is not included. Versioned replaceable allocation functions and replaceable deallocation functions are replaceable: a user-supplied non-member function with the same signature defined anywhere in the program and in any source file replaces the default version. Its declaration does not need to be visible. This means that when we replace the global new/delete functions, we do not need to declare them in .h, we only need to define them in .cpp. For a function that can be replaced, if multiple replacements for it are provided in the program, or it has inl

template void LOrR(T&) { std::cout << "L" << std::endl; } template void LOrR(T&&) { std::cout << "R" << std::endl; } template voidFuncA(

When implementing TypeTraits, I discovered that std::is_scoped_enum of the standard library will not be officially installed until C++23, so I found a clever alternative by looking through the source code of Unreal Engine 4, similar to the following implementation: NAMESPACE_PRIVATE_BEGIN uint8(&Resolve(int64 ))[2]; uint8 Resolve(…); template struct TIsEnumConvertibleToInt : TBoolCons

PS: Due to a bug in WP-Editor.md, the $ symbol in the script is not displayed and needs to be added manually. PS: This bug disappears after switching to WP Githuber MD. Solution cmake_minimum_required (VERSION 3.8) # Main project string(REGEX REPLACE ".*/(.*)" "\\1" CURRENT_FOLDER ${CMAKE_CURRENT_SOURCE_DIR}) project ($

Locking principles and rules 10.1 When multi-threaded processes access shared resources in parallel, they must be locked to protect shared resources including global variables, static variables, shared memory, files, etc. It is recommended to encapsulate an object like a smart pointer to manage the lock. For example, we encapsulate an auto_lock, apply for the lock during construction, and release the lock during destruction to ensure that you will not forget to unlock it. Rule 10.2 The lock has a single responsibility. Each lock only locks a unique shared resource. In this way, the lock application can be guaranteed to be single, and the locking scope can be better ensured to be as small as possible. For shared global resources, there should be one lock for each type or resource according to actual needs. In this way, this lock only locks the code that accesses this resource. Usually such code will be