Difference between pre-increment and post-increment in a loop?

Question

Is there a difference in ++i and i++ in a for loop? Is it simply a syntax thing?

Answer 1

In C# there is no difference when used in a for loop.

for (int i = 0; i < 10; i++) { Console.WriteLine(i); }

outputs the same thing as

for (int i = 0; i < 10; ++i) { Console.WriteLine(i); }

As others have pointed out, when used in general i++ and ++i have a subtle yet significant difference:

int i = 0;
Console.WriteLine(i++);   // Prints 0
int j = 0;
Console.WriteLine(++j);   // Prints 1

i++ reads the value of i then increments it.

++i increments the value of i then reads it.

Answer 2

i++ ; ++i ; both are similar as they are not used in an expression.

class A {

     public static void main (String []args) {

     int j = 0 ;
     int k = 0 ;
     ++j;
     k++;
    System.out.println(k+" "+j);

}}

prints out :  1 1

Answer 3

For i's of user-defined types, these operators could (but should not) have meaningfully different sematics in the context of a loop index, and this could (but should not) affect the behavior of the loop described.

Also, in c++ it is generally safest to use the pre-increment form (++i) because it is more easily optimized. (Scott Langham beat me to this tidbit. Curse you, Scott)

Answer 4

The question is:

Is there a difference in ++i and i++ in a for loop?

The answer is: No.

Why does each and every other answer have to go into detailed explanations about pre and post incrementing when this is not even asked?

This for-loop:

for (int i = 0; // Initialization
     i < 5;     // Condition
     i++)       // Increment
{
   Output(i);
}

Would translate to this code without using loops:

int i = 0; // Initialization

loopStart:
if (i < 5) // Condition
{
   Output(i);

   i++ or ++i; // Increment

   goto loopStart;
}

Now does it matter if you put i++ or ++i as increment here? No it does not as the return value of the increment operation is insignificant. i will be incremented AFTER the code's execution that is inside the for loop body.