exception

问题 I have following piece of code (PHP 7.3.16) which retrieves some data from database (MySQL): // db credentials $dbhost = "localhost"; $dbuser = "user"; $dbpass = "password"; $dbname = "database"; // pdo $dsn = "mysql:host=".$dbhost.";dbname=".$dbname.";charset=utf8"; $options = [ PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC, PDO::ATTR_EMULATE_PREPARES => false ]; $pdo = new PDO($dsn, $dbuser, $dbpass, $options); // run sql query $sql = "SELECT

问题 I have a function template like this: template <typename T> constexpr auto myfunc() noexcept { return T{}; } Is this function template guaranteed to be noexcept because of copy elision? If an exception is thrown inside the constructor, does this happen inside or outside the function? 回答1: All that copy elision does is eliminate the actual copy or move. Everything happens "as-if" things happen without the copy-elision taking place (except for the copy itself, of course). The construction

问题 mutex.lock(); try { foo(); // can throw exception } catch (...) { mutex.unlock(); throw; } mutex.unlock(); To guaranty the unlock i must call mutex.unlock() in catch block and in normal case. Is there any option to avoid duplication? Thank You 回答1: What you are looking for is a mutex wrapper like std::lock_guard: #include <mutex> std::mutex _mutex; void call_foo() { std::lock_guard<std::mutex> lock(_mutex); try { foo(); // can throw exception } catch (...) { // the mutex is unlocked here...

问题 I have a python function that runs other functions. def main(): func1(a,b) func2(*args,*kwargs) func3() Now I want to apply exceptions on main function. If there was an exception in any of the functions inside main, the function should not stop but continue executing next line. In other words, I want the below functionality def main(): try: func1() except: pass try: func2() except: pass try: func3() except: pass So is there any way to loop through each statement inside main function and apply

问题 I have a python function that runs other functions. def main(): func1(a,b) func2(*args,*kwargs) func3() Now I want to apply exceptions on main function. If there was an exception in any of the functions inside main, the function should not stop but continue executing next line. In other words, I want the below functionality def main(): try: func1() except: pass try: func2() except: pass try: func3() except: pass So is there any way to loop through each statement inside main function and apply

问题 My message "Divide by 0 error" is not going through, instead I'm getting a normal ZeroDivisionError . #!/usr/bin/python t = raw_input("do you want to play a game?[y/n]" ) #r = raw_input("Please enter a number") #e = raw_input("Please enter a number again") try: def di (a, b): return a/b except ZeroDivisionError: print "Divide by 0 Error" while t == "y": u = raw_input("Please enter / sign ") if u == "/": r = int(raw_input("Please enter a number")) try: e = int(raw_input("Please enter a number

问题 I am working on a Task parallel problem that I have many Tasks that may or may not throw Exception. I want to process all the tasks that finishes properly and log the rest. The Task.WhenAll propage the Task exception without allowing me to gather the rest results. static readonly Task<string> NormalTask1 = Task.FromResult("Task result 1"); static readonly Task<string> NormalTask2 = Task.FromResult("Task result 2"); static readonly Task<string> ExceptionTk = Task.FromException<string>(new

问题 I am working on a Task parallel problem that I have many Tasks that may or may not throw Exception. I want to process all the tasks that finishes properly and log the rest. The Task.WhenAll propage the Task exception without allowing me to gather the rest results. static readonly Task<string> NormalTask1 = Task.FromResult("Task result 1"); static readonly Task<string> NormalTask2 = Task.FromResult("Task result 2"); static readonly Task<string> ExceptionTk = Task.FromException<string>(new

问题 This question already has answers here : Java - find the first cause of an exception (9 answers) Closed 10 months ago . I am trying to call saveOrUpdate() in hibernate to save data. Since columns have unique index, so its throws ConstraintViolationException when I look through via Eclipse debugger. Since root cause could be different for different exception while inserting data to table. I wanted to know, how can I loop / traverse through getCause() to check what is the root cause of

问题 This is a follow up to this question Consider the following code #include <variant> int add_(int a, int b){ return a+b; } float add_(float a, float b){ return a+b; } float add_(int a, float b){ return a+b; } float add_(float a, int b){ return a+b; } using Number = std::variant<int, float>; Number add(Number const& lhs, Number const& rhs ){ return std::visit( []( auto& lhs_, auto& rhs_ )->Number { return {add_( lhs_, rhs_ )}; }, lhs, rhs ); } int main(){ Number a = 1.f; Number b = 2.f; Number