Thread: What is wrong with my code? using structs and fprintf

I am working on a function for my project that formats the output of complex(imaginary) numbers, but when I run it, its not being formatted as i thought it would be.
the struct being used is:

Code:

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

And I am unable to change the type of re and im, in the struct
the function i have written for this so far is:

Code:

void output_complex(FILE *outf,complex z)
{
   if(z.im == 0)
   {
      fprintf(outf,"%f", z.re);
   }
   if(z.re == 0)
   {
      if(z.im == 1)
      {
	 fprintf(outf,"i"); 
      }
      fprintf(outf,"%fi", z.im);
   }
    if(z.im == 1)
   {
      fprintf(outf,"%f + i", z.re);
   }
   if(z.im < 0)
   {
      if(z.im == -1)
      {
	 fprintf(outf,"%f - i", z.re);
      }
      z.im *= -1;  
      fprintf(outf,"%f - %fi", z.re, z.im);
   }
   fprintf(outf,"%f + %fi", z.re, z.im);
}

and there is this program that checks to see if the expected output is the same as the output of the function and this is what I got when I ran it for this function:
Output Function Errors:
expected: 1 + 2i
actual: 1.000000 + 2.000000i
expected: 3
actual: 3.0000003.000000 + 0.000000i
expected: 4i
actual: 4.000000i0.000000 + 4.000000
expected: i
actual:
expected: -2 + i
actual: i1.000000i0.000000 + i0.0000
expected: 4 - 2i
actual: 0 + 1.000000i
expected: 3 + 2i
actual: -2.000000 + i-2.000000 + 1.0
expected: 2 - i
actual: 0000i

what am I doing wrong?

I don't really understand what it is you are trying to do. Why don't you just print the real and imaginary part.

Yeah, I noticed that but I posted first.

Originally Posted by Subsonics

Yeah, I noticed that but I posted first.

$!@%#@...so you did. <whine>Fine, I'll move my post...</whine>

Originally Posted by ashleyd

what am I doing wrong?

Honestly, I'd say you wrote a bunch of code for a problem and solution you don't fully understand. You need to start with a clear understanding of the problem and it's solution. Then, write down the solution on paper, in plain English. Work though your paper solution with these test cases, revising if necessary. Once that's done, start coding. I don't mean to sound insulting here, but are you familiar with using else and else if? Your solution will no doubt require at least one, if not both of those constructs (you can read up on them here and Google for more info).

It might help to break the problem up into some logical "chunks". Here are some questions to get you going in the right direction:

• When do I print the real part?
• When do I print a + or -?
• When do I print the imaginary part?
• When do I print a number in the imaginary part? Should this number have an 'i' after it?
• When do I print just an 'i'?

Yeah this is a duplicate by mistake, caused by slow page loading
so any ideas of what i can do to fix this?
i am trying to print out an equation, in the form a + bi

Did you read the link I provided (red text in my previous post, #5)? You need to think through the solution. What answers did you come up with to the questions in my previous post? I'd feel a lot more comfortable giving you a huge hint if I thought you were making a sincere effort to figure this out.

Thanks for the advice, I was able to get it working by putting a return; statement after each fprintf statement