What is the difference between ostringstream and std::stringstream

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

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.

TheautokeywordinC deducesthetypeofavariablefromitsinitializer,makingcodecleanerandmoremaintainable.1.Itreducesverbosity,especiallywithcomplextypeslikeiterators.2.Itenhancesmaintainabilitybyautomaticallyadaptingtotypechanges.3.Itisnecessaryforunnamed

Use std::source_location::current() as the default parameter to automatically capture the file name, line number and function name of the call point; 2. You can simplify log calls through macros such as #defineLOG(msg)log(msg,std::source_location::current()); 3. You can expand the log content with log level, timestamp and other information; 4. To optimize performance, function names can be omitted or location information can be disabled in the release version; 5. Column() and other details are rarely used, but are available. Using std::source_location can significantly improve the debugging value of logs with extremely low overhead without manually passing in FIL

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.

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.

memory_order_relaxed is suitable for scenarios where only atomicity is required without synchronization or order guarantee, such as counters, statistics, etc. 1. When using memory_order_relaxed, operations can be rearranged by the compiler or CPU as long as the single-threaded data dependency is not destroyed. 2. In the example, multiple threads increment the atomic counter, because they only care about the final value and the operation is consistent, the relaxed memory order is safe and efficient. 3. Fetch_add and load do not provide synchronization or sequential constraints when using relaxed. 4. In the error example, the producer-consumer synchronization is implemented using relaxed, which may cause the consumer to read unupdated data values because there is no order guarantee. 5. The correct way is

Singleton pattern ensures that a class has only one instance and provides global access points. C 11 recommends using local static variables to implement thread-safe lazy loading singletons. 1. Use thread-safe initialization and delayed construction of static variables in the function; 2. Delete copy construction and assignment operations to prevent copying; 3. Privatization of constructs and destructors ensures that external cannot be created or destroyed directly; 4. Static variables are automatically destructed when the program exits, without manually managing resources. This writing method is concise and reliable, suitable for loggers, configuration management, database connection pooling and other scenarios. It is the preferred singleton implementation method under C 11 and above standards.