處理復數時，可以使用結構體來表示復數的實部和虛部，然后定義相應的操作函數來實現復數的加減乘除等運算。下面是一個簡單的示例代碼：

#include <stdio.h>

typedef struct {
    double real;
    double imaginary;
} Complex;

Complex add(Complex c1, Complex c2) {
    Complex result;
    result.real = c1.real + c2.real;
    result.imaginary = c1.imaginary + c2.imaginary;
    return result;
}

Complex subtract(Complex c1, Complex c2) {
    Complex result;
    result.real = c1.real - c2.real;
    result.imaginary = c1.imaginary - c2.imaginary;
    return result;
}

Complex multiply(Complex c1, Complex c2) {
    Complex result;
    result.real = c1.real * c2.real - c1.imaginary * c2.imaginary;
    result.imaginary = c1.real * c2.imaginary + c1.imaginary * c2.real;
    return result;
}

void printComplex(Complex c) {
    if (c.imaginary >= 0) {
        printf("%.2f + %.2fi\n", c.real, c.imaginary);
    } else {
        printf("%.2f - %.2fi\n", c.real, -c.imaginary);
    }
}

int main() {
    Complex c1 = {3.0, 4.0};
    Complex c2 = {1.0, -2.0};

    Complex sum = add(c1, c2);
    Complex difference = subtract(c1, c2);
    Complex product = multiply(c1, c2);

    printf("Sum: ");
    printComplex(sum);

    printf("Difference: ");
    printComplex(difference);

    printf("Product: ");
    printComplex(product);

    return 0;
}

這段代碼定義了一個Complex結構體，包含了實部和虛部，然后定義了加法、減法、乘法等操作函數，并在main函數中測試了這些操作。通過結構體和函數的封裝，可以方便地處理復數的運算。