Convert char to int in C#

I have a char in c#:

char foo = '2';

Now I want to get the 2 into an int. I find that Convert.ToInt32 returns the actual decimal value of the char and not the number 2. The following will work:

int bar = Convert.ToInt32(new string(foo, 1));

int.parse only works on strings as well.

Is there no native function in C# to go from a char to int without making it a string? I know this is trivial but it just seems odd that there's nothing native to directly make the conversion.

This will convert it to an int:

char foo = '2';
int bar = foo - '0';

This works because each character is internally represented by a number. The characters '0' to '9' are represented by consecutive numbers, so finding the difference between the characters '0' and '2' results in the number 2.

Interesting answers but the docs say differently:

> Use the GetNumericValue methods to > convert a Char object that represents > a number to a numeric value type. Use > Parse and TryParse to convert a > character in a string into a Char > object. Use ToString to convert a Char > object to a String object.

http://msdn.microsoft.com/en-us/library/system.char.aspx

Has anyone considered using int.Parse() and int.TryParse() like this

int bar = int.Parse(foo.ToString());

Even better like this

int bar;
if (!int.TryParse(foo.ToString(), out bar))
{
    //Do something to correct the problem
}

It's a lot safer and less error prone

char c = '1';
int i = (int)(c - '0');

and you can create a static method out of it:

static int ToInt(this char c)
{
	return (int)(c - '0');
}

Try This

char x = '9'; // '9' = ASCII 57

int b = x - '0'; //That is '9' - '0' = 57 - 48 = 9

By default you use UNICODE so I suggest using faulty's method

int bar = int.Parse(foo.ToString());

Even though the numeric values under are the same for digits and basic Latin chars.

This converts to an integer and handles unicode

CharUnicodeInfo.GetDecimalDigitValue('2')

You can read more here.

Principle:

char foo = '2';
int bar = foo & 15;

The binary of the ASCII charecters 0-9 is:

0   -   0011 0000
1   -   0011 0001
2   -   0011 0010
3   -   0011 0011
4   -   0011 0100
5   -   0011 0101
6   -   0011 0110
7   -   0011 0111
8   -   0011 1000
9   -   0011 1001

and if you take in each one of them the first 4 LSB (using bitwise AND with 8'b00001111 that equals to 15) you get the actual number (0000 = 0,0001=1,0010=2,... )

Usage:

public static int CharToInt(char c)
{
    return 0b0000_1111 & (byte) c;
}

The real way is:

> int theNameOfYourInt = (int).Char.GetNumericValue(theNameOfYourChar);

"theNameOfYourInt" - the int you want your char to be transformed to.

"theNameOfYourChar" - The Char you want to be used so it will be transformed into an int.

Leave everything else be.

I am agree with @Chad Grant

Also right if you convert to string then you can use that value as numeric as said in the question

int bar = Convert.ToInt32(new string(foo, 1)); // => gives bar=2

I tried to create a more simple and understandable example

char v = '1';
int vv = (int)char.GetNumericValue(v); 

char.GetNumericValue(v) returns as double and converts to (int)

More Advenced usage as an array

int[] values = "41234".ToArray().Select(c=> (int)char.GetNumericValue(c)).ToArray();

First convert the character to a string and then convert to integer.

var character = '1';
var integerValue = int.Parse(character.ToString());

I'm using Compact Framework 3.5, and not has a "char.Parse" method. I think is not bad to use the Convert class. (See CLR via C#, Jeffrey Richter)

char letterA = Convert.ToChar(65);
Console.WriteLine(letterA);
letterA = 'あ';
ushort valueA = Convert.ToUInt16(letterA);
Console.WriteLine(valueA);
char japaneseA = Convert.ToChar(valueA);
Console.WriteLine(japaneseA);

Works with ASCII char or Unicode char

Comparison of some of the methods based on the result when the character is not an ASCII digit:

char c1 = (char)('0' - 1), c2 = (char)('9' + 1); 

Debug.Print($"{c1 & 15}, {c2 & 15}");                   				// 15, 10
Debug.Print($"{c1 ^ '0'}, {c2 ^ '0'}");                   				// 31, 10
Debug.Print($"{c1 - '0'}, {c2 - '0'}");                                 // -1, 10
Debug.Print($"{(uint)c1 - '0'}, {(uint)c2 - '0'}");                     // 4294967295, 10
Debug.Print($"{char.GetNumericValue(c1)}, {char.GetNumericValue(c2)}"); // -1, -1

Use this:

public static string NormalizeNumbers(this string text)
{
    if (string.IsNullOrWhiteSpace(text)) return text;

    string normalized = text;

    char[] allNumbers = text.Where(char.IsNumber).Distinct().ToArray();

    foreach (char ch in allNumbers)
    {
        char equalNumber = char.Parse(char.GetNumericValue(ch).ToString("N0"));
        normalized = normalized.Replace(ch, equalNumber);
    }

    return normalized;
}

One very quick simple way just to convert chars 0-9 to integers: C# treats a char value much like an integer.

char c = '7'; (ascii code 55) int x = c - 48; (result = integer of 7)

Use Uri.FromHex.
And to avoid exceptions Uri.IsHexDigit.

char testChar = 'e';
int result = Uri.IsHexDigit(testChar) 
               ? Uri.FromHex(testChar)
               : -1;

I was searched for the most optimized method and was very surprized that the best is the easiest (and the most popular answer):

public static int ToIntT(this char c) =>
	c is >= '0' and <= '9'?
		c-'0' : -1;

There a list of methods I tried:

c-'0' //current
switch //about 25% slower, no method with disabled isnum check (it is but performance is same as with enabled)
0b0000_1111 & (byte) c; //same speed
Uri.FromHex(c) /*2 times slower; about 20% slower if use my isnum check*/ (c is >= '0' and <= '9') /*instead of*/ Uri.IsHexDigit(testChar)
(int)char.GetNumericValue(c); // about 20% slower. I expected it will be much more slower.
Convert.ToInt32(new string(c, 1)) //3-4 times slower

Note that isnum check (2nd line in the first codeblock) takes ~30% of perfomance, so you should take it off if you sure that c is char. The testing error was ~5%

This worked for me:

int bar = int.Parse("" + foo);

I've seen many answers but they seem confusing to me. Can't we just simply use Type Casting.

For ex:-

int s;
char i= '2';
s = (int) i;