Question

Example: Simple program of swapping two nos.

 int a = 10;
 int b = 20;
 a = a+b;
 b = a-b;
 a = a-b;

Now in the following piece of code:

 a=a+b-(b=a);

I mean What is the difference b/w these two piece of codes?

Addition : What if the addition of these two exceed the legitimate limit of an Integer which is different in case of Java & C++?

Answer 1

A couple points:

• Code should first reflect your intentions. After all, it’s meant for humans to read. After that, if you really really must, you can start to tweak the code for performance. Most of all never write code to demonstrate a gimmick or bit twiddling hack.
• Breaking code onto multiple lines has absolutely no impact on performance.
• Don’t underestimate the compiler’s optimizer. Just write the code as intuitively as possible, and the optimizer will ensure it has the best performance.

In this regard, the most descriptive, intuitive, fastest code, is:

std::swap(a, b);