Complex usage in C

complex.c

#include <stdio.h>
#include <complex.h>
/*
Compile option : icc -std=c99 main.c -o main
*/
int main() {
    double complex a;

    a = 1.0 + I * 2.0;

    printf("%f + i%f\n", creal(a), cimag(a)); // 1.000 + i2.000

    return 0;
}