Iterating until int.MaxValue reached

Question

As a little test I wanted to see how long it would take to count to int.MaxValue in a C# console application. Every few hours I checked the progress. Last night when I thoug

Answer 1

Your for loop:

for (int counter=0; counter <=numToCountTo ; counter++)

is incorrect. It will execute while counter <= int.MaxValue which is ALWAYS true. When it increments it it will roll to int.MinValue and keep incrementing.

Change it to

for (int counter=0; counter < numToCountTo ; counter++)

or use a long for your loop counter:

for (long counter=0; counter <= numToCountTo ; counter++)

You can also use a do...while loop since the loop is executed before the breaking condition is evaluated:

int counter = 0;
do
{
   ...
   counter++;
}
while(counter < numToCountTo);

Answer 2

It's called an overflow - the integer wraps around to the lowest possible negative value.

If you want it to stop at maxInt you should replace the <= with a < - at present you can never stop the loop as counter can never be bigger can maxIni.

Answer 3

When you add 1 to an Int32.MaxValue you will end up with Int32.MinValue.

int a = Int32.MaxValue;
a++; // a is now -2147483648

Answer 4

It will continue because counter will never be > than int.MaxValue, if you do int.MaxValue+1 it will wrap down to int.MinValue.

Thus, your for condition is always true.

An alternative I would recommend is either use a larger datatype for your counter like long, or change your loop to:

int counter = -1;
for(;;) // while(true)
{
    counter++;
    Console.WriteLine("{0}", counter);

    if (counter == int.MaxValue) 
    {
        break;
    } 
}