How to rethrow exceptions in C++ function exception handling?

Exception rethrowing in C is used to rethrow an exception after catching it so that other parts of the program can handle it. The syntax is: try { ... } catch (const std::exception& e) { // Handle exceptions // ... // Rethrow exceptions throw; }. A caught exception can be rethrown in a catch block by using the throw keyword. This exception will terminate the function and let the superior function handle the exception.

Exception rethrowing in C function exception handling

In C, the exception handling mechanism allows Terminate a program gracefully or resume it. By using the try-catch statement, we can catch exceptions and perform specific error handling.

Sometimes, we may want to rethrow an exception after catching it so that other parts of the program can handle the exception. This can be achieved by using the throw keyword.

How to rethrow exceptions

The syntax for rethrowing exceptions is as follows:

try {
  // 可能会抛出异常的代码
}
catch (const std::exception& e) {
  // 处理异常
  // ...
  // 重抛异常
  throw;
}

In the catch block, use ## The #throw keyword can rethrow the caught exception. This will terminate the current function and let the superior function handle the exception.

Practical case

Consider the following code segment:

#include <iostream>

void fun1() {
  try {
    fun2();
  }
  catch (const std::logic_error& e) {
    std::cout << "Caught logic error in fun1: " << e.what() << std::endl;
    // 重抛异常以允许调用者处理
    throw;
  }
}

void fun2() {
  throw std::logic_error("Logic error in fun2");
}

int main() {
  try {
    fun1();
  }
  catch (const std::logic_error& e) {
    std::cout << "Caught logic error in main: " << e.what() << std::endl;
  }
  return 0;
}

Execution output:

Caught logic error in fun1: Logic error in fun2
Caught logic error in main: Logic error in fun2

In this In the example,

fun2() throws a std::logic_error exception. fun1() Catch the exception and rethrow it. main() The function then catches and handles the rethrown exception.

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