PHP Chinese garbled characters A brief analysis of the difference and efficiency between i++ and ++i in PHP

Let’s take a look at the basic differences first:

i++: First use the current value of i in the expression where i is located, and then add 1 to i.

++i: Let i add 1 first, and then add 1 to the expression where i is located. Use the new value of i in the expression

After watching some video tutorials, when writing for loops, ++i is written instead of i++. After searching online, it turns out that there is an efficiency issue

++i is equivalent to the following code

i += 1; 
return i; 

i++ is equivalent to the following code

j = i; 
i += 1; 
return j;

Of course, if the compiler will optimize out these differences, then the efficiency will be almost the same.

Let me tell you the difference between ++i and i++ in detail

1. The usage of ++i (take a=++i, i=2 as an example)

First add 1 to the i value (also That is, i=i+1), and then assign it to variable a (that is, a=i),

Then the final value of a is equal to 3, and the value of i is equal to 3.

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

2, the usage of i++ (take a=i++, i=2 as an example)

First assign the i value to variable a (also That is a=i), then the i value is increased by 1 (that is, i=i+1),

Then the final a value is equal to 2, and the i value is equal to 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 alone, it is equivalent to i=i+1

If assigned to a new variable, ++i first adds 1 to the value of i, and i++ first assigns i to the new variable. variable.

The above is the entire description of the differences and efficiency between i++ and ++i in PHP introduced by the editor. I hope it will be helpful to you. If you have any questions, please leave me a message and the editor will reply in time. Ours. Thank you very much for your support of this website!

The above introduces the Chinese garbled code in PHP and briefly analyzes the difference and efficiency of i++ and ++i in PHP, including the content of Chinese garbled code in PHP. I hope it will be helpful to friends who are interested in PHP tutorials.