异常 名称空间

#include <math.h>

#include <iostream>

using namespace std;

double triangle(double a, double b, double c) {
    double area;
    double s = (a + b + c) / 2;
    if (a + b <= c || a + c <= b || b + c <= a) throw a;
    area = sqrt(s * (s - a) * (s - b) * (s - c));
    return area;
}

int main() {
    double a, b, c;
    cin >> a >> b >> c;
    try {
        while (a > 0 && b > 0 && c > 0) {
            cout << triangle(a, b, c) << endl;
            cin >> a >> b >> c;
        }
    } catch (int) {
        cout << "a = " << a << " b = " << b << " c = " << c
             << ", that is not a trianle!\n";
    }

    return 0;
}

#include <iostream>
#include <string>

using namespace std;

void Demo1() {
    try {
        throw "hello";
    } catch (char) {
        cout << "catch(char)" << endl;
    } catch (int) {
        cout << "catch(int)" << endl;
    } catch (double) {
        cout << "catch(double)" << endl;
    } catch (...) {
        cout << "catch(...)" << endl;  // 捕获任意异常，或者叫匿名捕获异常
    }
}

void Demo2() {
    throw "hello";
    // throw string("D.T.Software");
}

int main() {
    Demo1();
    try {
        Demo2();
    } catch (char*) {
        cout << "catch(char*)" << endl;
    } catch (string) {
        cout << "catch(string)" << endl;
    }
}

#include <exception>
#include <iostream>

using namespace std;

class MyExecption : public exception {
   public:
    const char* what() const throw() { return "C++ Execption"; }
};

int main() {
    try {
        throw MyExecption();
    } catch (MyExecption& e) {
        cout << "My Exception caught" << endl;
        cout << e.what() << endl;
    } catch (exception& e) {
        cout << "other execption caught" << endl;
    }

    return 0;
}

#include <iostream>

using namespace std;

namespace first_space {
void func() { cout << "Inside first_space" << endl; }
}  // namespace first_space

namespace second_space {
void func() { cout << "Inside second_space" << endl; }
}  // namespace second_space

using namespace second_space;

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