How to use the try/catch block to catch exceptions (xtd.core)

Place any code statements that might raise or throw an exception in a try block, and place statements used to handle the exception or exceptions in one or more catch blocks below the try block. Each catch block includes the exception type and can contain additional statements needed to handle that exception type.

In the following example, a stream_reader opens a file called data.txt and retrieves a line from the file. Since the code might throw any of three exceptions, it's placed in a try block. Three catch blocks catch the exceptions and handle them by displaying the results to the console.

#include <xtd/xtd>

using namespace xtd;
using namespace xtd::io;

class process_file {
public:
  static void main() {
    try {
      block_scope_ (auto sr = stream_reader {"data.txt"}) {
        console::write_line("The first line of this file is {}", sr.read_line());
      }
    } catch (const file_not_found_exception& e) {
      console::write_line("The file was not found: '{}'", e);
    } catch (const directory_not_found_exception& e) {
      console::write_line("The directory was not found: '{}'", e);
    } catch (const io_exception& e) {
      console::write_line("The file could not be opened: '{}'", e);
    }
  }
};

startup_(process_file::main);

The xtd::startupsafe class, hidden behind the startup keyword, catches exceptions that are not handled by catch blocks. If an exception is caught by the xtd::startup_safe class, one of the following results may occur, depending on the application type running:

A Debug dialog box appears.
The program stops execution and a dialog box with exception information appears.
An error prints out to the standard error output stream.

[!note] Most code can throw an exception, and some exceptions, such as xtd::out_of_memory_exception, can be thrown by xtd itself at any time. Although applications are not required to handle these exceptions, you should be aware of this possibility when writing libraries intended for use by others. To find out when to place code in a try block, see Best practices for exceptions.

How to use the try/catch block to catch exceptions (xtd.core)

See also