So my friend gave me some source code to start out with so I could review and understand it and I have a question about it, but since he's not online I thought I would try here, mainly I don't quite understand this line.
num += i;
Essentially, this is the same as
num = num + i
right?
If you need more details please tell me! I look forward to hearing your replies soon.
Yes. It is exactly the same (assuming you are talking about the built-in +=). In fact, this is how += is defined in the language specification.
Doesn't your favorite C++ book cover this topic?
Essentially yes, but it is more efficient. For basic types, like integers, using num += i increments the value of num directly, whereas num = num + i creates a temporary of the value of num, increments it, and then assigns it back to num.
From ISO C++03 (Section 5.17/7)
The behavior of an expression of the form E1 op= E2 is equivalent to E1 = E1 op E2 except that E1 is evaluated only once.
What will really happen there, as posted before, depends on the language. If one assumes C++, and that num is an integer, then as others have posted and as you have
num += i;
is equivalent to
num = num + i;
But it is really up to the class to determine that behavior in c++ / c#. You will essentially call the "+=" operator on the num object for the i object type. This should, in a good design, be the same as first performing the "+" operator, and then performing the = operator in the manner above. But it doesn't have to be:
class foo
{
bool operator += (int i) {return false;}
}
foo num;
int i;
bool result = num += i;
In that example, num will be unchanged, and result will be false.