CODEWITHSUNDEEP
.netcastingboolean
hawbsl
hawbsl

Reputation: 16003

Can .NET convert "Yes" & "No" to boolean without If?

You would think there would be a way using DirectCast, TryCast, CType etc but all of them seem to choke on it e.g.:

CType("Yes", Boolean)

You get:

System.InvalidCastException - Conversion from string "Yes" to type 'Boolean' is not valid.

Upvotes: 21

Views: 37287

Answers (13)

MarredCheese
MarredCheese

Reputation: 20811

I like switch for this since it's simple and easily scales as needed. The default pattern catches empty strings and nulls without any fuss. I also like extension methods, so I end up with this:

public static class StringExtensions
{
    public static bool ToBool(this string str)
    {
        return str?.ToLower() switch
        {
            "true" => true,
            "yes" => true,
            "y" => true,
            "t" => true,
            "1" => true,
            _ => false
        };
    }   
}

Usage

"Yes".ToBool();  // true
"no".ToBool();   // false
"".ToBool();     // false

string s = null;
s.ToBool();      // false

Upvotes: 2

VyTre
VyTre

Reputation: 146

public static bool IsBoolean(string strValue)
{
    return !string.IsNullOrEmpty(strValue) && ("1/YES/TRUE".IndexOf(strValue, StringComparison.CurrentCultureIgnoreCase) >= 0);
}

Upvotes: 0

thelost
thelost

Reputation: 6694

No, but you could do something like:

bool yes = "Yes".Equals(yourString);

Upvotes: 20

STLDev
STLDev

Reputation: 6164

I like the answer that @thelost posted, but I'm reading values from an ADO.Net DataTable and the casing of the string in the DataTable can vary.

The value I need to get as a boolean is in a DataTable named childAccounts in a column named Trades.

I implemented a solution like this:

bool tradeFlag = childAccounts["Trade"].ToString().Equals("yes", StringComparison.InvariantCultureIgnoreCase);

Upvotes: 0

ScottJamesSDF
ScottJamesSDF

Reputation: 63

C# 6+ version:

public static bool StringToBool(string value) => 
    value.Equals("yes",           StringComparison.CurrentCultureIgnoreCase) ||
    value.Equals(bool.TrueString, StringComparison.CurrentCultureIgnoreCase) || 
    value.Equals("1");`

Upvotes: 5

dburtsev
dburtsev

Reputation: 1

    private bool StrToBool(string value)
    {   // could be yes/no, Yes/No, true/false, True/False, 1/0
        bool b = false;
        if (value.Equals("yes", StringComparison.CurrentCultureIgnoreCase) || value.Equals(Boolean.TrueString, StringComparison.CurrentCultureIgnoreCase) || value.Equals("1"))
        {
            b = true;
        }
        else if (value.Equals("no", StringComparison.CurrentCultureIgnoreCase) || value.Equals(Boolean.FalseString, StringComparison.CurrentCultureIgnoreCase) || value.Equals("0"))
        {
            b = false;
        }
        else
        {   // we should't be here 
            b = false;
        }
        return b;
    }

Upvotes: 0

FirebirdUSA
FirebirdUSA

Reputation: 1

Here is a simple way to get this done.

rv.Complete = If(reader("Complete") = "Yes", True, False)

Upvotes: -1

Simon A Cousins
Simon A Cousins

Reputation: 1

Public Function TrueFalseToYesNo(thisValue As Boolean) As String
    Try
        If thisValue Then
            Return "Yes"
        Else
            Return "No"
        End If
    Catch ex As Exception
        Return thisValue.ToString
    End Try
End Function

Upvotes: -2

sshow
sshow

Reputation: 9094

private static bool GetBool(string condition)
{
    return condition.ToLower() == "yes";
}

GetBool("Yes"); // true
GetBool("No"); // false

Or another approach using extension methods

public static bool ToBoolean(this string str)
{
    return str.ToLower() == "yes";
}

bool answer = "Yes".ToBoolean(); // true
bool answer = "AnythingOtherThanYes".ToBoolean(); // false

Upvotes: 4

Mubashar
Mubashar

Reputation: 12658

You Can't. But you should use it as

bool result = yourstring.ToLower() == "yes";

Upvotes: 2

Regent
Regent

Reputation: 5602

Slightly off topic, but I needed once for one of my classes to display 'Yes/No' instead of 'True/False' in a property grid, so I've implemented YesNoBooleanConverter derived from BooleanConverter and decorating my property with <TypeConverter(GetType(YesNoBooleanConverter))> _...

Upvotes: 2

Rubys
Rubys

Reputation: 3207

Using this way, you can define conversions from any string you like, to the boolean value you need. 1 is true, 0 is false, obviously.
Benefits: Easily modified. You can add new aliases or remove them very easily.
Cons: Will probably take longer than a simple if. (But if you have multiple alises, it will get hairy)

enum BooleanAliases {
      Yes = 1,
      Aye = 1,
      Cool = 1,
      Naw = 0,
      No = 0
 }
 static bool FromString(string str) {
      return Convert.ToBoolean(Enum.Parse(typeof(BooleanAliases), str));
 }
 // FromString("Yes") = true
 // FromString("No") = false
 // FromString("Cool") = true

Upvotes: 31

slugster
slugster

Reputation: 49984

If you think about it, "yes" cannot be converted to bool because it is a language and context specific string.

"Yes" is not synonymous with true (especially when your wife says it...!). For things like that you need to convert it yourself; "yes" means "true", "mmmm yeeessss" means "half true, half false, maybe", etc.

Upvotes: 86

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