What is a way to represent complex numbers in C?

Question

Without using the complex.h header file, suppose I want to create my own header file where I will define a variable argument function,

taking value 0 if I did not insert any value from the keyboard,
becoming a real number if I input only one value,
and a complex number if I input two values.

How can such a complex number be implemented? I have been thinking about the "i" symbol for the imaginary part. How can it appear? Is there any nice way to write a complex number?

Also I need to define addition in the complex field. How can that be done?

I think I mentioned I cannot use the complex.h header file. The task is to CREATE my own header file. — Landon Carter, Jan 06 '15 at 14:54
Could this be relevant? http://stackoverflow.com/questions/5093566 — Reti43, Jan 06 '15 at 14:56
Just want do you mean by "variable argument function"? C does not have overloaded functions, and variadic functions require *your function code* to know how many arguments there are (example, *printf* knows from its format string), so you probably want 3 functions. Or one function taking a string, which it parses? — hyde, Jan 19 '15 at 20:20

score 4 · Answer 1 · edited Jan 06 '15 at 15:51

4

You should use a structure to represent it:

struct complex{
   int real;
   int imaginary;
};

now you can create an instance:

struct complex num;

and set its fields:

num.real = 3; //real part is now set to 3
num.imaginary = 5; //imaginary part is now set to 5

edited Jan 06 '15 at 15:51

Utkan Gezer

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answered Jan 06 '15 at 15:20

antonpuz

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score 3 · Answer 2 · answered Jan 06 '15 at 14:50

3

Why not create a struct with two fields for the Re and Im parts?

The i-notation is only a representation.

Then you can write functions that take two variables of the strcut type you created and return the added numbers as the same struct type.

answered Jan 06 '15 at 14:50

Ramon Hofer

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Sorry but I am a beginner at C. By "two fields" do you mean two components? And, if so, how can the final representation happen so that the final answer also is a complex number? – Landon Carter Jan 06 '15 at 14:52
See Anton.P's answer. He described a struct with the two fields real and imaginary. Now you can create a function: complex function(complex a, complex b) { ... } – Ramon Hofer Jan 06 '15 at 15:33

What is a way to represent complex numbers in C?

2 Answers2