C range-based for loop tutorial

C folderexpressions is a feature introduced by C 17 to simplify recursive operations in variadic parameter templates. 1. Left fold (args...) sum from left to right, such as sum(1,2,3,4,5) returns 15; 2. Logical and (args&&...) determine whether all parameters are true, and empty packets return true; 3. Use (std::cout

The answer is: Use the std::string constructor to convert the char array to std::string. If the array contains the intermediate '\0', the length must be specified. 1. For C-style strings ending with '\0', use std::stringstr(charArray); to complete the conversion; 2. If the char array contains the middle '\0' but needs to convert the first N characters, use std::stringstr(charArray,length); to clearly specify the length; 3. When processing a fixed-size array, make sure it ends with '\0' and then convert it; 4. Use str.assign(charArray,charArray strl

The most common method of finding vector elements in C is to use std::find. 1. Use std::find to search with the iterator range and target value. By comparing whether the returned iterator is equal to end(), we can judge whether it is found; 2. For custom types or complex conditions, std::find_if should be used and predicate functions or lambda expressions should be passed; 3. When searching for standard types such as strings, you can directly pass the target string; 4. The complexity of each search is O(n), which is suitable for small-scale data. For frequent searches, you should consider using std::set or std::unordered_set. This method is simple, effective and widely applicable to various search scenarios.

TodebugaC applicationusingGDBinVisualStudioCode,configurethelaunch.jsonfilecorrectly;keysettingsincludespecifyingtheexecutablepathwith"program",setting"MIMode"to"gdb"and"type"to"cppdbg",using"ex

The system endianness can be detected by a variety of methods, the most commonly used is the union or pointer method. 1. Use a union: Assign uint32_t to 0x01020304, if the lowest address byte is 0x04, it is a small endian, and if it is 0x01, it is a big endian; 2. Use pointer conversion: Assign uint16_t to 0x0102, read the byte order through the uint8_t pointer, [0]==0x02 and [1]==0x01 is a small endian, otherwise it is a big endian; 3. Compilation-time detection: define the constexpr function to determine whether the (char)&int variable is 1, and combine ifconstexpr to determine the endian order during the compilation period; 4. Runtime macro encapsulation: use (char*)&amp

std::mutex is used to protect shared resources to prevent data competition. In the example, the automatic locking and unlocking of std::lock_guard is used to ensure multi-thread safety; 1. Using std::mutex and std::lock_guard can avoid the abnormal risks brought by manual management of locks; 2. Shared variables such as counters must be protected with mutex when modifying multi-threads; 3. RAII-style lock management is recommended to ensure exception safety; 4. Avoid deadlocks and multiple locks in a fixed order; 5. Any scenario of multi-thread access to shared resources should use mutex synchronization, and the final program correctly outputs Expected:10000 and Actual:10000.

Install the Boost library, 2. Write code for DNS resolution using Boost.Asio, 3. Compile and link the boost_system library, 4. Run the program to output the IP address parsed by www.google.com; this example shows how Boost.Asio simplifies network programming in C, implements cross-platform, type-safe synchronous DNS queries through io_context and tcp::resolver, and supports IPv4 and IPv6 address resolution, and finally prints all resolution results.

If it is iterating when deleting an element, you must avoid using a failed iterator. ①The correct way is to use it=vec.erase(it), and use the valid iterator returned by erase to continue traversing; ② The recommended "erase-remove" idiom for batch deletion: vec.erase(std::remove_if(vec.begin(),vec.end(), condition), vec.end()), which is safe and efficient; ③ You can use a reverse iterator to delete from back to front, the logic is clear, but you need to pay attention to the condition direction. Conclusion: Always update the iterator with the erase return value, prohibiting operations on the failed iterator, otherwise undefined behavior will result.