#include <stdio.h>
#include <stdlib.h>

typedef struct {
    double re;
    double im;
} complex;

void add(complex* c1, const complex* c2) {
    c1->re += c2->re;
    c1->im += c2->im;
}

void mul(complex* c1, const complex* c2) {
    c1->re = c1->re*c2->re - c1->im*c2->im;
    c1->im = c1->re*c2->im + c2->re*c1->im;
}

void con(complex* c1) {
    c1->im = -c1->im;
}

//argc = number of arguments (including exetuable name)
int main(int argc, char** argv) {
    if (argc<3) {
        printf("Zu wenige Argumente");
        exit(1);
    }
    FILE* fp1 = fopen(argv[1],"r");
    FILE* fp2 = fopen(argv[2],"r");
    
    if (!fp1) {
        printf("Datei \"%s\" existiert nicht.\n", argv[1]);
        exit(1);
    }
    if (!fp2) {
        printf("Datei \"%s\" existiert nicht.\n", argv[2]);
        exit(1);
    }
    
    complex scalar_prod = {0};
    
    complex x,y;
    while(fscanf(fp1, "%lf + %lfi", &x.re, &x.im) == 2 && 
        fscanf(fp2, "%lf + %lfi", &y.re, &y.im) == 2) {
        con(&y);
        mul(&x, &y);
        add(&scalar_prod, &x);
    }
    
    printf("%f + %fi\n", scalar_prod.re, scalar_prod.im);
    
    fclose(fp1);
    fclose(fp2);
    
}