Thread: fprintf and outf

I am currently working on a project, and am having trouble understanding part of the code
A section of this code is:

Code:

complex input_complex(FILE *infile)
{
  complex z = {0,0};
  double re = 0, im = 0;
  char op, ch;

  fscanf(infile,"%lf %c%lf%c",&re,&op,&im,&ch);

  if (infile != stdin && !good(im,op,ch)) {
    printf("Improperly formed complex number in input file; goodbye\n");
    exit(1);
  }
	
  while(!good(im,op,ch)) {
    printf("Illegal input for complex number; try again\n");
    fscanf(infile,"%lf %c%lf%c",&re,&op,&im,&ch);
    
  }
  
  z.re = re;
  if (op == '+')
    z.im = im;
  else
    z.im = -im;
  
  return z;
}

int equal_complex(complex z, complex w)
{
  return z.re == w.re && z.im == w.im;
}

double mag_squared(complex z)
{
  return z.re*z.re + z.im*z.im;
}

complex scalar_multiple(double c, complex z)
{
  complex w = ZERO;
  w.re = c*z.re;
  w.im = c*z.im;;
  return w;
}

complex conjugate(complex z)
{
  complex w = ZERO;
  w.re = z.re; 
  w.im = -z.im;
  return w;
}

/*****************************************************************/
/* FUNCTIONS FOR YOU TO IMPLEMENT - JUST STUBS FOR NOW           */
/*****************************************************************/


void output_complex(FILE *outf,complex z)
{
  z.re = 2;
  fprintf(outf,"2+2i");
}

The top section is what was given and is to not be changed, and the function output_complex is what i have to edit
and looking at the code that is in output_complex, i am confused with what fprintf(outf,"2+2i"); means, and most importantly what outf specifically means

Originally Posted by ashleyd

Code:

void output_complex(FILE *outf,complex z)
{
  z.re = 2;
  fprintf(outf,"2+2i");
}

and looking at the code that is in output_complex, i am confused with what fprintf(outf,"2+2i"); means, and most importantly what outf specifically means

Look up the syntax for fprintf() in your C library documentation.

outf is a file handle that's passed into the function.

is there a way for me to find out exactly what the outf file handle does, because after looking at my documentation it says that the outf writes output to the stream pointed to by outf, which did not help my understanding much

It's just a variable that C uses to refer to some file. Your output_complex function doesn't care what file it's writing to, only that outf is a valid file handle that can be written to. Here's a tutorial on file handling in C: Cprogramming.com - Tutorials - C File I/O. Google around for more tutorials and try some simple practice problems.

Originally Posted by ashleyd

is there a way for me to find out exactly what the outf file handle does, because after looking at my documentation it says that the outf writes output to the stream pointed to by outf, which did not help my understanding much

For your puposes ... stream = an open disk file.