After successfully building and running your code, you should see the following in the UART1 Output window:

Code Analysis

(NOTE: Line numbers correspond to those in the provided solution file.)

Line 12-15
This is the type declaration for the complex number structure. There are two members, representing the real (re) and imaginary (im) parts, and the type name is complex.

Line 20
This is a variable declaration. We are creating an array of structures of type complex. The array has three elements, and we are initializing the array as we are declaring it. Note that the syntax we use to initialize the array is essentially the same as initializing a multidimensional array. So, in a more algebraic form, our array now looks like this:
x[0] = 1.1 + j1.2
x[1] = 2.1 + j2.2
x[2] = 3.1 + j3.2

Line 48
STEP 1: At this point, we are now inside the loop, and will be accessing a complex number on each pass. STEP 1 has us multiplying the real part of the current array element by 10. The easiest way to do this is to use the *= operator. The structure member may be accessed by using the dot notation with the array variable and its index:

x[i].re *= 10;

Line 55
STEP 2: has us performing a similar operation to step 1, but this time, we will be multiplying the imaginary part by 5:

x[i].im *= 5;

Line 60
This line prints out the recently modified complex numbers in an algebraic format:

printf("%f + j%f\n", x[i].re, x[i].im);

Since the complex number’s members are both floating point types, we need to use %f as our placeholder/formatting characters in the printf() control string. Then, the arguments used are the same as those used on Line 48 and Line 55 to specify a structure member that is part of an array element.