Usage differences between php I ++ and ++ I

This I ++ and ++ I usage is mainly used in the cycle. This is often because there are no small errors in usage. Let's introduce the differences between I ++ and ++ I.

1. Usage of ++ I (using a = ++ I, I = 2 as an example)

Add the I value to 1 (that is, I = I + 1) and then assign it to variable a (that is, a = I ),

The final a value is 3, and the I value is 3.

So a = ++ I is equivalent to I = I + 1, a = I

2. I ++ usage (take a = I ++, I = 2 as an example)

First, assign the I value to variable a (that is, a = I), and then add 1 (that is, I = I + 1) to the I value ),

Then, the final a value is 2, and the I value is 3.

So a = I ++ is equivalent to a = I, I = I + 1

3. ++ I and I ++

A = ++ I is equivalent to I ++, a = I

A = I ++ is equivalent to a = I, I ++

4. When ++ I and I ++ are used independently, they are equivalent to I = I + 1.