Question

I tried to run this code but it says error, I don't know what am I missing.

#include <stdio.h>
struct complex {
float real, imag;
};
main()
{
struct complex a,b,c;
extern void c_mult(struct complex a,
struct complex b,
struct complex *c);
a.real =1.0;
a.imag =1.0;
b.real=1.0;
b.imag =1.0;
c_mult(a,b,&c);
printf("%f%+f\n", c.real, c.imag);
exit(0);
}

Answer 1

Rate my solution and comment if any doubt

Code:

#include<stdio.h>
//stdlib is included for exit function
// as stdlib is not included in your program there was warning
#include<stdlib.h>
// complex struct is used for storing real and imaginary numbers
struct complex {
float real, imag;
};
main(){
   // declaing variables of structure complex
   struct complex a,b,c;
   // c_mult function declaration
   // as you did not define the function you got error
   extern void c_mult(struct complex a,
   struct complex b,
   struct complex *c);
   // (a+bi)(c+di)=(ac-bd)+(bc+ad)
   a.real =1.0; //a
   a.imag =1.0; //b
   b.real=1.0; //c
   b.imag =1.0; //d
   //c_mult(a,b,&c) is function calling
   c_mult(a,b,&c);
   printf("%f%+f\n", c.real, c.imag);
   //exit(0) will exit the function
   exit(0);
}
extern void c_mult(struct complex a,struct complex b,struct complex *c){
   //I wrote the below function thiking that
   //First imaginary number(a) is muliplied with second(b)
   //and stored in c
   //Change the function based on your requirement
   // ac-bd
   c->real=(a.real*b.real)-(a.imag*b.imag);
   // bc+ad
   c->imag=(a.imag*b.real)+(a.real*b.imag);
}

Screenshot:

Output: