Exceptions用于处理Run-time Error;
//文件读取的异常捕获伪代码 try{ open the file; determine its size; allocate that much memory; read the file into memory; close the file; }catch(fileOpenFailed){ doSomething; }catch(sizeDeterMinationFailed){ doSomething; }catch(memoryAllocationFailed){ doSomething; }catch(readFailed){ doSomething; }catch(fileCloseFailed){ doSomething; }
异常,让函数发现有自己无法处理的错误时抛出一个异常