cppreference.com > C/C++ Keywords > throw throw Syntax:
      try {
      statement list;
      }
      catch( typeA arg ) {
      statement list;
      }
      catch( typeB arg ) {
      statement list;
      }
      ...
      catch( typeN arg ) {
      statement list;
      }
The throw statement is part of the C++ mechanism for exception handling. This statement, together with the try and catch statements, the C++ exception handling system gives programmers an elegant mechanism for error recovery. You will generally use a try block to execute potentially error-prone code. Somewhere in this code, a throw statement can be executed, which will cause execution to jump out of the try block and into one of the catch blocks. For example:
       try {
         cout << "Before throwing exception" << endl;
         throw 42;
         cout << "Shouldn't ever see this" << endl;
       }
       catch( int error ) {
         cout << "Error: caught exception " << error << endl;
       }
Related topics: catch try