纯C语言版:

#include<stdio.h>
#include<math.h>

struct cpxNum
{
    double a,b;
};
cpxNum cplus(cpxNum c1,cpxNum c2);      //加
cpxNum cmilus(cpxNum c1,cpxNum c2);     //减
cpxNum cmultiply(cpxNum c1,cpxNum c2);  //乘
cpxNum cdivide(cpxNum c1,cpxNum c2);    //除

int main()
{
    cpxNum c1, c2,c3;
    double real,imag;
    printf("请输入第一个复数的实部和虚部: ");
    scanf("%lf %lf",&real,&imag);
    printf("您生成的第一个复数是: ");
    c1.a=real;
    c1.b=imag;
    printf("%f+%fi\n",real,imag);

    printf("请输入第二个复数的实部和虚部: ");
    scanf("%lf %lf",&real,&imag);
    printf("您生成的第二个复数是: ");
    c2.a=real;
    c2.b=imag;
    printf("%f+%fi\n",real,imag);
    printf("***********复数运算测试*************\n");
    printf("c1 + c2的结果是: ");
    c3=cplus(c1, c2);
    if(c3.b<0)
        printf("%lf - %lfi\n",c3.a,fabs(c3.b));
    else
        printf("%lf + %lfi\n",c3.a,c3.b);

    printf("c1 - c2的结果是: ");;
    c3=cmilus(c1, c2);
    if(c3.b<0)
        printf("%lf - %lfi\n",c3.a,fabs(c3.b));
    else
        printf("%lf+%lfi\n",c3.a,c3.b);

    printf("c1 * c2的结果是: ");
    c3=cmultiply(c1, c2);
    if(c3.b<0)
        printf("%lf - %lfi\n",c3.a,fabs(c3.b));
    else
        printf("%lf+%lfi\n",c3.a,c3.b);

    printf("c1 / c2的结果是: ");
    c3=cdivide(c1, c2);
    if(c3.b<0)
        printf("%lf - %lfi\n",c3.a,fabs(c3.b));
    else
        printf("%lf+%lfi\n",c3.a,c3.b);

    printf("**********复数运算测试结束***********\n");
    return 0;
}
cpxNum cplus(cpxNum c1,cpxNum c2)
{
    cpxNum c3;
    c3.a=c1.a+c2.a;
    c3.b=c1.b+c2.b;
    return c3;
}

cpxNum cmilus(cpxNum c1,cpxNum c2)
{
    cpxNum c3;
    c3.a=c1.a-c2.a;
    c3.b=c1.b-c2.b;
    return c3;
}
cpxNum cmultiply(cpxNum c1,cpxNum c2)
{
    cpxNum c3;
    c3.a=c1.a*c2.a-c1.b*c2.b;
    c3.b=c1.a*c2.b+c1.b*c2.a;
    return c3;
}
cpxNum cdivide(cpxNum c1,cpxNum c2)
{
    cpxNum c3;
    c3.a=c1.a*c2.a+c1.b*c2.b;
    c3.b=c1.b*c2.a-c1.a*c2.b;
    return c3;
}
//优化了虚部的表示

用结构体挺简单的;

贴张运行效果图: