C++ function call exception handling: exceptions in parameter passing and return values

Summary: Exception handling in function calls involves: Parameter passing exception: When the passed parameters cause an exception, the exception is passed to the calling function. Return value exception: The function throws an exception through the return value, which is passed directly to the calling function. Practical example: MyClass::func() throws std::invalid_argument exception when the function parameter is an empty string, and the main() function captures and handles the exception.

C Function call exception handling: exceptions in parameter transfer and return value

In C, during function call Exceptions may involve parameter passing and return value handling. In order to handle these exceptions correctly, it is crucial to understand the mechanism behind them.

Exceptions in parameter passing

During a function call, if the passed parameter itself raises an exception, the exception will be passed to the calling function. This is because the parameter is passed as a normal object, just like other data types.

For example, consider the following function:

void func(int& x) {
  if (x == 0) throw std::invalid_argument("x cannot be zero");
  ...
}

If a value of 0 is passed when calling this function, an std::invalid_argument exception will be thrown. This exception will be passed to the calling function and needs to be caught and handled by the calling function.

Exceptions in return values

Functions can also throw exceptions through their return values. This is accomplished by specifying whether a function may throw an exception using the noexcept keyword. If a function is declared noexcept, it is guaranteed not to throw any exceptions. Otherwise, it may throw an exception.

If a function throws an exception, it will be passed directly to the calling function. For example, consider the following function:

int func() noexcept {
  return 1;
}

If this function throws an exception, the calling function will catch and handle the exception.

Practical Case

To illustrate how to handle exceptions in parameter passing and return values, consider the following example:

#include <iostream>
#include <string>

class MyClass {
public:
  void func(const std::string& s) {
    if (s.empty()) throw std::invalid_argument("s cannot be empty");
  }
};

int main() {
  try {
    MyClass obj;
    obj.func("");  // 抛出 std::invalid_argument
  } catch (std::exception& ex) {
    std::cout << "Caught exception: " << ex.what() << std::endl;
  }

  return 0;
}

In this example, MyClass::func() When the s parameter of the function is an empty string, an std::invalid_argument exception is thrown. main() The function caught and handled this exception.

Conclusion

Understanding the mechanics of function call exception handling in C is critical to writing robust code. By properly handling exceptions in parameter passing and return values, you can ensure that your application will still function normally under abnormal conditions.

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