System.OverflowException, and how to fix it

Question

I was making a fake encryption program and when trying to convert a string into a int32 and i get the following message System.OverflowException. The error message is at the Convert.ToInt32(textnumbers);

 static void encryption(string text) { byte[] nums = Encoding.ASCII.GetBytes(text); int[] en = new int[nums.Length]; for (int i = 0; i < nums.Length; i++) { en[i] = nums[i] * 2 + 5; } string textnumbers = string.Join("", en); Console.WriteLine(textnumbers); int num = Convert.ToInt32(textnumbers); string hexValue = num.ToString("x"); Console.WriteLine(hexValue); } static void Main(string[] args) { encryption("abcde"); Console.ReadLine(); }

Does this answer your question?How can I convert String to Int? — Soheila Tarighi
– Soheila Tarighi, Commented Apr 6, 2020 at 15:34
We don't know what you typed. It would be more helpful to replace Console.ReadLine() with a string literal. Also, hopefully this is just a toy/fun project because it's not really encryption. — Damien_The_Unbeliever
– Damien_The_Unbeliever, Commented Apr 6, 2020 at 15:35
What is the value of textnumbers when the exception occurs? — user1666620
– user1666620, Commented Apr 6, 2020 at 15:35
The actual error is because textnumber is either over the max value of 2147483647 or under the min value of -2147483648, my assumption is it's over that max value. You could try using ToInt64 and see if that fits... — Trevor
– Trevor, Commented Apr 6, 2020 at 15:38
Consider using Int32.TryParse instead. That gives you the advantage of knowing whether it succeeded without throwing an exception. — devsmn
– devsmn, Commented Apr 6, 2020 at 15:47

John H · Accepted Answer · 2020-04-06 16:11:43Z

The important part is to pay attention to the exception message that the System.OverflowException produces, which is:

Value was either too large or too small for an Int32.

That gives you a big clue as to what the problem is.

Next, if you take a look at the value of textnumbers after the for loop has been completed, you'll see its value is 199201203205207. As Çöđěxěŕ mentioned, the maximum value a signed 32-bit integer can store is 2147483647, so the exception is telling you a 32-bit integer isn't large enough to store the value you want.

To fix this, you can use a 64-bit integer:

long num = Convert.ToInt64(textnumbers);

long represents a signed 64-bit integer, and can store values in the range -9223372036854775808 to 9223372036854775807, inclusive, which can comfortably store 199201203205207.

If ever you need to know the range of values a numeric type can represent, you can examine its MinValue and MaxValue properties (e.g. int.MinValue, or long.MaxValue).

One thing though: you should learn to work with the debugger, because it makes fixing this kind of problem by yourself trivial. It's worth investing that time so you can self-service problems like this, without relying on others.

Sina Hoseinkhani · Accepted Answer · 2020-04-06 16:02:27Z

Your program generates '199201203205207' which is greater than what you could fit in int. try changing it to long ,also use Convert.ToInt64(textnumbers):

static void encryption(string text) { byte[] nums = Encoding.ASCII.GetBytes(text); int[] en = new int[nums.Length]; for (int i = 0; i < nums.Length; i++) { en[i] = nums[i] * 2 + 5; } string textnumbers = string.Join("", en); Console.WriteLine(textnumbers); long num = Convert.ToInt64(textnumbers); string hexValue = num.ToString("x"); Console.WriteLine(hexValue); } static void Main(string[] args) { encryption("abcde"); Console.ReadLine(); }

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