1. Usage of i (take a= i, i=2 as an example)
First add the value of i 1 (i.e. i=i 1), and then assign it to variable a (i.e. a=i),
Then the final a value is equal to 3, and the i value is equal to 3.
So a= i is equivalent to i=i 1, a=i
2. Usage of i (take a=i, i=2 as an example)
First Assign the i value to the variable a (that is, a=i), then add 1 to the i value (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, they are equivalent to i=i 1
If assigned to a new variable, i first Add 1 to the value of i, and assign i to the new variable first.