Difference Between i++ and ++i and their performance issue

Hello Listeners, today I'll show you the difference between i++ and ++i and their performance issue, cause many of my juniors have asked me to clarify between i++ and ++i. 

Difference between i++ and ++i

Their is a difference between i++ and ++i . 

++i
++i will increment the value of i variable then returns the incremented i variable. To clarify just see the example of code - 

 i = 1;
 j = ++i;

 printf("i = %d, j = %d", i, j)
 
 // Output =>
 i = 2, j = 2

i++
i++ will increment the value of i variable then returns the original i variable. To clarify just see the example of code - 

 i = 1;
 j = i++;

 printf("i = %d, j = %d", i, j)
 
 // Output =>
 i = 2, j = 1

Look, in this example j is not incremented, j is the original i's value.

When we've to use i++ or ++i

This is a question I've brought from many people, when we've use i++ or ++i.
You've seen the difference of them. Now it's your choice. You can use any of them i++ or ++i. For a for loop, they works just same.
But as a programmer or in common programming ++i is always better than i++. ++i never goes wrong. See the performance issue part.

Performance issue i++ vs ++i

First need to tell for a small project theirs no difference between i++ or ++i.

But potentially i++ could be slower than ++i , Because i++ will create an extra copy and that's need a memory, which is not by ++i.

Why: See the example again

 
i = 1; //1
++i;  // 2

i = 1; //1
i++;  // 1

Look here,

1. In first case, there is no temporary value to store, it just print the incremented value
2. In second case i++, it's not printing the incremented value. It's store the value in another temp file. That is really unnecessary and takes memory.

And another thing, though i++ needs a temp variable, it's not any hard task for our computer today and in real life basically they are the same.
both the i++ or ++i containing file create the same object file and theirs no difference.
There is no compiler difference today between ++i or i++.

See a compiler object both i++ and ++i

After generating an assembler of both ++i and  i++ by this way,

$ gcc -c i++.c ++i.c
$ gcc -S i++.c ++i.c

Assembler output of both are the same, like -

$ md5 i++.s ++i.s
MD5 (i++.s) = 90f620dda862cd0205cd5db1f2c8c06e
MD5 (++i.s) = 90f620dda862cd0205cd5db1f2c8c06e

$ md5 *.o
MD5 (++i.o) = dd3ef1408d3a9e4287facccec53f7d22
MD5 (i++.o) = dd3ef1408d3a9e4287facccec53f7d22

But it's obviously better to use ++i over i++.

Conclusion on ++i and i++: 

Since it seems that i++ take a local variable copy and ++i don't, in today's computer can manipulate them same manner and theirs really don't performance issue.

Hopefully, your conflict has cleared now about ++i or i++. You can use both depending on your needs.

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