i++ Vs. ++i

i++ Vs. ++i

  2월 06, 2022    Eunhan's library

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what is difference between prefix operator (++i) and postfix operator (i++)

Definition

Some programming languages provide short code for increase or decrease value.
By using the prefix and postfix operators, you can write code faster.

Purpose

Thus, i=i+1 is same as i+=1 is same as i++ and ++i.
But, what is difference between prefix operator (++i) and postfix operator (i++)?

Inner code

Example 1

int x = 2;
int y = 2;
  
System.out.println(x * y++); //4
System.out.println(x); //2
System.out.println(y); //3

Because i++ happens after run the code,

1. run $x*y$
2. print $x*y=2*2=4$
3. add 1 to y

Example 2

int x = 2;
int y = 2;

System.out.println(x * ++y); //6
System.out.println(x); //2
System.out.println(y); //3

Because ++i happens before run the code,

1. add 1 to y
2. run $x*y$
3. print $x*y=2*3=6$

conclusion

• ++i wil give you slightly better speed and memory.
• If you are working with backend(such as Java), this is not important. However, if you are working with console games(such as C++), this is important.
• i++ will happen after run the code
• ++i will happen before run the code