Re-identifying an integer's value in a for loop?

[LN7oGNh0]

Is it bad to identify an integer's value and then re-identify it in a for loop? I always fear unidentified variables and I dint know whether this will cause me problems once I get better. Examples:

int i = 109;

for (int i = 0; i < 99; i++) //Made i equal to 0 after assigning it 89
{
cout << i << "\n";
}

Example #2:

int i = 543;

for (int i = 0; i < 100; i++); //made i a different value, and it is lower than the condition in the for statement.
{
cout << i << "\n";
}

Will the for loop in example 2 even start? (I would assume it does because i is reinitialized to 0.)

Is this ok in do-while loops and while loops as well?

Thanks!

[Peter87]

The i defined on line 1 is a completly different variable from the i defined on line 3. The i that is being used on line 5 is the i that was defined on line 3. It is better to use different variable names to avoid confusion.

[LN7oGNh0]

thank you.