用C或C++语言设计并实现一个可进行复数运算的演示程序。

在C++中，我们可以创建一个简单的复数类（ComplexNumber），用于基本的复数加法、减法、乘法和除法操作。以下是一个基础版本的示例：

#include <iostream>
using namespace std;

class ComplexNumber {
private:
    double real;   // 实部
    double imag;   // 虚部

public:
    // 构造函数
    ComplexNumber(double r = 0, double i = 0) : real(r), imag(i) {}

    // 访问器和设置器
    double getReal() const { return real; }
    double getImaginary() const { return imag; }

    void setReal(double r) { real = r; }
    void setImaginary(double i) { imag = i; }

    // 复数运算
    ComplexNumber add(ComplexNumber other) const {
        double new_real = real + other.real;
        double new_imag = imag + other.imag;
        return ComplexNumber(new_real, new_imag);
    }

    ComplexNumber subtract(ComplexNumber other) const {
        double new_real = real - other.real;
        double new_imag = imag - other.imag;
        return ComplexNumber(new_real, new_imag);
    }

    ComplexNumber multiply(ComplexNumber other) const {
        double new_real = real * other.real - imag * other.imag;
        double new_imag = real * other.imag + imag * other.real;
        return ComplexNumber(new_real, new_imag);
    }

    // 如果除数不是0，进行除法运算；否则抛出异常
    ComplexNumber divide(ComplexNumber other) const {
        if (other.getReal() == 0 && other.getImaginary() == 0)
            throw runtime_error("Cannot divide by zero.");
        
        double denominator = other.getReal() * other.getReal() + other.getImaginary() * other.getImaginary();
        double new_real = (real * other.getReal() + imag * other.getImaginary()) / denominator;
        double new_imag = (imag * other.getReal() - real * other.getImaginary()) / denominator;
        return ComplexNumber(new_real, new_imag);
    }

    // 打印复数
    void print() const {
        cout << "(" << real << ", " << imag << ") ";
    }
};

int main() {
    ComplexNumber c1(2, 3);
    ComplexNumber c2(4, 5);

    c1.print(); cout << "+";
    c2.print(); cout << " = ";
    ComplexNumber sum = c1.add(c2);
    sum.print();

    cout << "\nSubtraction:\n";
    c1.print(); cout << "-";
    c2.print(); cout << " = ";
    ComplexNumber sub = c1.subtract(c2);
    sub.print();

    cout << "\nMultiplication:\n";
    c1.print(); cout << "*";
    c2.print(); cout << " = ";
    ComplexNumber mul = c1.multiply(c2);
    mul.print();

    try {
        cout << "\nDivision:\n";
        c1.print(); cout << "/"; 
        c2.print(); cout << " = ";
        ComplexNumber div = c1.divide(c2);
        div.print();
    } catch (const exception& e) {
        cerr << "Error: " << e.what() << endl;
    }

    return 0;
}

在这个例子中，我们定义了一个复数类，包含构造函数、访问器、赋值器以及基本的算术运算方法。`main()`函数展示了如何创建复数对象，并进行各种运算。