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Programming Tip Of The Day #2 – Difference Between i++ and ++i

To some, this should seem a bit obvious and if I am insulting your intelligence by discussing it, I am sorry. But, one of the main reasons I want to discuss this topic is, I was asked this question in a job interview for Lockheed Martin.

What is the difference between i++ and ++i?

The answer is actually quite simple.

i++ first evaluates the value of i and then increments it

++i increments the value of i and then evaluates it

Here is a brief example to demonstrate what I mean.

// Example: i++ 
$i = 5;
echo "The value of i is " . $i++ ;
// Output "The value of i is 5"
// i = 6
 
// Example: ++i 
$i = 5;
echo "The value of i is " . ++$i;
// Output "The value of i is 6"
// i = 6

So, now if you are ever asked about this in an interview, you will have a response.

Happy programming!