Some understanding regarding Extension Methods

Question

I just collected some knowledge regarding and it seems to be very little to understand following scenario.

I have 2 classes. One has Main method and other has two Extension Methods as follow.

Class having Main

class Program { static void Main(string[] args) { string uuu = "214"; Console.WriteLine(uuu.SplitMe().AddMe()); Console.ReadKey(); } }

Extension Class

static class ExtensionClass { public static char[] SplitMe(this string value) { return value.ToCharArray(); } public static long AddMe(this char[] value) { int sum = 0; for (int i = 0; i<value.Length ; i++) { sum += Convert.ToInt32(value[i]); } return sum; } }

I was expecting, in following line

Console.WriteLine(uuu.SplitMe().AddMe());

output of uuu.SplitMe() to be char[] of {'2','1','4'} and result of complete line to be printed as 7 (2+1+4) but it is 151 on my console. Could you please elaborate how its being calculated?

Thanks.

'2' is has not the value of 2. If you convert '2' to a number, you will get the ACII code for the letter '2'. If you want to parse a number use Int32.Parse. — Florian
– Florian, Commented May 26, 2014 at 18:26
@thefiloe .NET generally uses the Unicode character set and the UTF-16 and UTF-8 encodings. You can only get ASCII codes if you explicitly use ASCII conversion methods (or depend on their numerical equivalence but that leads to errors with characters not supported by ASCII). — Tom Blodget
– Tom Blodget, Commented May 26, 2014 at 21:18
If you do something like (int)'2' you will get the ACII code. — Florian
– Florian, Commented May 27, 2014 at 9:15

Reed Copsey · Accepted Answer · 2014-05-26 18:17:20Z

The issue is that a System.Char value of '2' has an integer value of 50, not 2. As such, you're summing {'2','1','4'}, which have values of {50, 49, 52}, which in turn becomes 151.

You could convert the characters to numbers matching their value via:

sum += int.Parse(value[i].ToString());

However, this will raise an exception if you pass a string that contains non-numeric characters.

Codor · Accepted Answer · 2014-05-26 18:18:00Z

The value of a char containing 2 is not 2, but 50, as its position in the ASCII table is used as its value; the same goes for the other numbers, which explains the unexpected result.

thumbmunkeys · Accepted Answer · 2014-05-26 18:18:39Z

Convert.ToInt32 does not convert the numeric string value, but the specified Unicode character to the equivalent 32-bit signed integer.

Muhammad Zaighum · Accepted Answer · 2014-05-26 18:23:55Z

Because the ascii value of 2 is 50 1 is 49 and 4 is 52. so it is adding those values..

you need to change your code

public static long AddMe(this char[] value) { int sum = 0; for (int i = 0; i < value.Length; i++) { sum += value[i]-48; } return sum; }

or you can do this also

sum += int.Parse(value[i].ToString());

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