try-catch statement

The basic syntax (1) shows the basic components of a try-catch block. First, the keyword try initiates a try-block in which statements can be executed. Note that the try-block, from the opening curly-brace to its closing, follows the same scoping rules as any other scope (e.g. variables declared within the try-block are not available outside of it, including from the catch-block that follows). Then, the catch statement acts as a specifier of the type of exception to be caught if thrown from within the try-block. The exception-decl has the same syntax as the parameter declaration within a single-parameter function declaration (except that the type cannot by void, an incomplete type, or an rvalue-reference (desde C++11)). Finally, the compound-statement { statements }  which follow the catch-statement is called the exception-handler and contains statements to be executed in response to the exception that was caught. Typical exception-handling code includes logging the error, employing an alternative method to what was attempted in the try-block, or re-packaging the exception into another thrown exception with additional information.

Syntax (5) is called a function-try-block and can be used to enclose an entire function body inside a try-block (with catch-blocks following it). This is especially useful to catch exceptions which could be thrown during the execution of a constructor's initialization list (construction of sub-objects of a class), in fact, it is the only way to do so. This function-try-block syntax is seldom used in any other context because it has no advantage as compared to a traditional try-catch block, and the resulting syntax is generally unappealing (and unfamiliar to most).