浙大版《C语言程序设计（第3版）》题目集 习题9-2 计算两个复数之积 (15分)

#include <stdio.h>
struct complex
{
    int real;
    int imag;
};
struct complex multiply(struct complex x, struct complex y);
int main()
{
    struct complex product, x, y;
    scanf("%d%d%d%d", &x.real, &x.imag, &y.real, &y.imag);
    product = multiply(x, y);
    printf("(%d+%di) * (%d+%di) = %d + %di\n",
           x.real, x.imag, y.real, y.imag, product.real, product.imag);
    return 0;
}
struct complex multiply(struct complex x, struct complex y)
{
    struct complex answer;
    answer.real = x.real * y.real - x.imag * y.imag;
    answer.imag = x.real * y.imag + y.real * x.imag;
    return answer;
}