How to make a dropdown list of all cultures (but no repeats)

I'm trying to make 2 dropdown lists.

The top one offers all cultures, (but no repeats). Example: English, Spanish, Filipino

After selecting from the top list the bottom list will show any specific types.

I right now I use this code for my top list.

foreach (CultureInfo cultureInfo in CultureInfo.GetCultures(CultureTypes.NeutralCultures))

However it does not show Filipino (Philippines) I'd rather not use GetCultures(CultureTypes.AllCultures)) because it shows too many at once.

It seems like I may need to load NeutralCultures into an IList. Then iterate through AllCultures to make sure it's ThreeLetterISOLanguageName is in the list, if not add it.

There a best practice for this?

Thanks

回答1

Look at the reference for the different CultureTypes values. It tells you what is included for each.

I guess you want everything that's in all but the specific cultures? You could either combine all non-specific cultures into a set or get all cultures and exclude the specific ones. The second approach would be easiest to express in LINQ:

var cultures = CultureInfo.GetCultures(CultureTypes.AllCultures)
                          .Except(CultureInfo.GetCultures(CultureTypes.SpecificCultures));

Though it seems that since CultureTypes has the flags attribute, we could also just mask out the SpecificCultures when getting them.

var cultures = CultureInfo.GetCultures(
    CultureTypes.AllCultures & ~CultureTypes.SpecificCultures
);

@aron: I'm not sure I understand what you are saying. The first part of the name is just the ISO 639-1 code code while the second part is the ISO 3166 code. ISO 639-1 code alone refers to a language (a neutral culture not associated with a specific region). Though the Czech Republic (cs-CZ) uses the the Czech language (cs), they are not equivalent. Both of those are specific cultures and should not be listed here. If it is, it is probably a culture object that was created by you (which is included).

– Jeff Mercado

May 11, 2011 at 3:22

Bitwise and shift operators (C# reference)

The following operators perform bitwise or shift operations with operands of the integral numeric types or the char type:

Unary ~ (bitwise complement) operator
Binary << (left shift), >> (right shift), and >>> (unsigned right shift) operators
Binary & (logical AND), | (logical OR), and ^ (logical exclusive OR) operators

Those operators are defined for the int, uint, long, and ulong types. When both operands are of other integral types (sbyte, byte, short, ushort, or char), their values are converted to the int type, which is also the result type of an operation. When operands are of different integral types, their values are converted to the closest containing integral type. For more information, see the Numeric promotions section of the C# language specification. The compound operators (such as >>=) don't convert their arguments to int or have the result type as int.

The &, |, and ^ operators are also defined for operands of the bool type. For more information, see Boolean logical operators.

Bitwise and shift operations never cause overflow and produce the same results in checked and unchecked contexts.

Bitwise complement operator ~

The ~ operator produces a bitwise complement of its operand by reversing each bit:

uint a = 0b_0000_1111_0000_1111_0000_1111_0000_1100;
uint b = ~a;
Console.WriteLine(Convert.ToString(b, toBase: 2));
// Output:
// 11110000111100001111000011110011

You can also use the ~ symbol to declare finalizers. For more information, see Finalizers.

Convert an integer to a binary string with leading zeros

I need to convert int to bin and with extra bits.

string aaa = Convert.ToString(3, 2);

it returns 11, but I need 0011, or 00000011.

How is it done?

回答1

11 is binary representation of 3. The binary representation of this value is 2 bits.

3 = 2⁰ * 1 + 2¹ * 1

You can use String.PadLeft(Int, Char) method to add these zeros.

// convert number 3 to binary string. 
// And pad '0' to the left until string will be not less then 4 characters
Convert.ToString(3, 2).PadLeft(4, '0') // 0011
Convert.ToString(3, 2).PadLeft(8, '0') // 00000011