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(C++17) 未捕获异常 uncaught_exceptions

ai 2025/7/28 3:57:58

文章目录

- 🐾前言
- 🐾实例
- - 🪝工具类
  - 🪝测试
- ⭐END
- - 🌟交流方式

🐾前言

从 C++11 其有 std::uncaught_exception 用于判断当前线程是否有未捕获的异常。而这个函数只是返回 bool 仅能查看是否存在未捕获异常。

因此到了 C++17 被弃用，在 C++20 中移除。C++17 引入了 int std::uncaught_exceptions() 可以获得具体的数量。

std::uncaught_exception, std::uncaught_exceptions - cppreference.com

🐾实例

🪝工具类

其实这个非常简单，最常用的就是在析构函数的时候，进行获取判断。

因此可以写这么一个工具类。当然，是选择在判断出有异常还是没异常的时候触发这个 action 还是两种状态下都注册一个，都是可以的。

#include <exception>
#include <functional>class ExcCatch {
private:const int             count = 0;std::function<void()> action;public:ExcCatch(const std::function<void()>& action = {}): count(std::uncaught_exceptions()), action(action) {}~ExcCatch() {if (count != std::uncaught_exceptions()) {if (action) {action();}}}
};

🪝测试

此处是用 vscode 中的 Copilot 所生成的测试代码。

简单看看使用方式就行了。

#include <exception>
#include <functional>class ExcCatch {
private:const int             count = 0;std::function<void()> action;public:ExcCatch(const std::function<void()>& action = {}): count(std::uncaught_exceptions()), action(action) {}~ExcCatch() {if (count != std::uncaught_exceptions()) {if (action) {action();}}}
};#include <atomic>
#include <iostream>
#include <stdexcept>// Helper for test output
#define ASSERT_TRUE(cond, msg)                      \if (!(cond)) {                                  \std::cout << "[FAIL] " << msg << std::endl; \} else {                                        \std::cout << "[PASS] " << msg << std::endl; \}
#define ASSERT_FALSE(cond, msg) ASSERT_TRUE(!(cond), msg)// Test that ExpCatch does not call action if no exception is thrown
void test_NoException_ActionNotCalled() {std::atomic<bool> called{false};{ExcCatch guard([&] { called = true; });}ASSERT_FALSE(called, "NoException_ActionNotCalled");
}// Test that ExpCatch calls action if exception is thrown
void test_Exception_ActionCalled() {std::atomic<bool> called{false};try {ExcCatch guard([&] { called = true; });throw std::runtime_error("test");} catch (...) {// Exception is caught here}ASSERT_TRUE(called, "Exception_ActionCalled");
}// Test that ExpCatch works with empty action
void test_EmptyAction_NoCrash() {try {ExcCatch guard;throw std::runtime_error("test");} catch (...) {// Should not crash}std::cout << "[PASS] EmptyAction_NoCrash" << std::endl;
}// Test that ExpCatch does not call action if exception is thrown but not caught in scope
void test_ExceptionNotCaughtInScope_ActionCalled() {std::atomic<bool> called{false};auto              test_func = [&] {ExcCatch guard([&] { called = true; });throw std::runtime_error("test");};try {test_func();} catch (...) {// Exception is caught here}ASSERT_TRUE(called, "ExceptionNotCaughtInScope_ActionCalled");
}int main() {test_NoException_ActionNotCalled();test_Exception_ActionCalled();test_EmptyAction_NoCrash();test_ExceptionNotCaughtInScope_ActionCalled();return 0;
}