C complex number and printf

Question

How to print ( with printf ) complex number? For example, if I have this code:

#include 
#include 
int main(void)
{
    doubl         


        

Answer 1

Because the complex number is stored as two real numbers back-to-back in memory, doing

printf("%g + i%g\n", result);

will work as well, but generates compiler warnings with gcc because the type and number of parameters doesn't match the format. I do this in a pinch when debugging but don't do it in production code.

Answer 2

Let %+f choose the correct sign for you for imaginary part:

printf("%f%+fi\n", crealf(I), cimagf(I));

Output:

0.000000+1.000000i

Note that i is at the end.

Answer 3

printf("%f + i%f\n", creal(result), cimag(result));

I don't believe there's a specific format specifier for the C99 complex type.

Answer 4

Using GNU C, this works:

printf("%f %f\n", complexnum);

Or, if you want a suffix of "i" printed after the imaginary part:

printf("%f %fi\n", complexnum);