程序代码：

#include <stdio.h>
#include <complex.h>

int main(void)
{
    double _Complex a = 1.0 + 2.0*_Complex_I;
    double _Complex b = 3.0 + 4.0*_Complex_I;
    double _Complex c = a * b;
    printf( "%f + %fi\n", creal(c), cimag(c) );

    return 0;
}