Exception handling in C++ technology: What are the principles and key points of the exception propagation mechanism?

Exception propagation mechanism: When an exception occurs in a function, it will propagate to the upper function until it is caught or continues to propagate. Key points: 1) Exception throwing is implemented through throw; 2) Catching exceptions uses try-catch blocks; 3) Repropagating exceptions uses rethrow.

C Exception propagation mechanism in exception handling: principles and key points

Exception propagation mechanism

When an exception occurs in a function, it will be passed on to the function that calls the function. This process is called anomaly propagation.

The principle of exception propagation

• When an exception occurs in a function, it will throw an exception object.
• The function that calls this function is responsible for catching the exception or continuing to propagate it to the upper layer.
• During the exception propagation process, each function must decide whether to catch or continue to propagate the exception.

Key points of exception propagation

• try-catch block: Used to catch exceptions. This block should be placed around code segments that may throw exceptions.
• throw: Used to throw an exception object. This statement will terminate the current function and continue to propagate the exception to the upper layer.
• rethrow: Used to re-propagate an exception after catching it. This allows exceptions to continue to be propagated upwards.

Practical case

The following is a simple example showing the exception propagation mechanism:

#include <iostream>

using namespace std;

void f1() throw(int) {
  throw 42;
}

void f2() {
  try {
    f1();
  }
  catch (int e) {
    cout << "Caught an integer exception: " << e << endl;
  }
}

int main() {
  f2();
  return 0;
}

In this example:

• Functionf1() Throws an int type exception.
• Function f2() Use a try-catch block to catch this exception and print it to standard output.
• main() Function call f2(), if an exception is thrown in f1(), it will be f2() Capture and process.

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