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?

Also, you should check out string formatting characters, and how to set limits on them.Wikipedia's prinf page is a good place to start.