[c#] Why does Boolean.ToString output "True" and not "true"

true.ToString() 
false.toString();

Output:
True
False

Is there a valid reason for it being "True" and not "true"? It breaks when writing XML as XML's boolean type is lower case, and also isn't compatible with C#'s true/false (not sure about CLS though).

Update

Here is my very hacky way of getting around it in C# (for use with XML)

internal static string ToXmlString(this bool b)
{
    return b.ToString().ToLower();
}

Of course that adds 1 more method to the stack, but removes ToLowers() everywhere.

For Xml you can use XmlConvert.ToString method.

...because the .NET environment is designed to support many languages.

System.Boolean (in mscorlib.dll) is designed to be used internally by languages to support a boolean datatype. C# uses all lowercase for its keywords, hence 'bool', 'true', and 'false'.

VB.NET however uses standard casing: hence 'Boolean', 'True', and 'False'.

Since the languages have to work together, you couldn't have true.ToString() (C#) giving a different result to True.ToString() (VB.NET). The CLR designers picked the standard CLR casing notation for the ToString() result.

The string representation of the boolean true is defined to be Boolean.TrueString.

(There's a similar case with System.String: C# presents it as the 'string' type).

It's simple code to convert that to all lower case.

Not so simple to convert "true" back to "True", however.

true.ToString().ToLower() 

is what I use for xml output.

How is it not compatible with C#? Boolean.Parse and Boolean.TryParse is case insensitive and the parsing is done by comparing the value to Boolean.TrueString or Boolean.FalseString which are "True" and "False".

EDIT: When looking at the Boolean.ToString method in reflector it turns out that the strings are hard coded so the ToString method is as follows:

public override string ToString()
{
    if (!this)
    {
        return "False";
    }
    return "True";
}

It's simple code to convert that to all lower case.

Not so simple to convert "true" back to "True", however.

true.ToString().ToLower() 

is what I use for xml output.

This probably harks from the old VB NOT .Net days when bool.ToString produced True or False.

The reason true is "True" is because of Microsoft's strong bond with XML standards.

From Wikipedia: "Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format which is both human-readable and machine-readable."

Human-readable is subjective, but in the eyes of XML, using the word "One" in place of a number "1" is preferred. You'll notice this happens using enums, as the word gets serialized instead of its value ("FirstOption" instead of "0" or "1").

Likewise, text commonly follows CamelCasing. Therefore, instead of "string", XML prefers "String". This is why Boolean.TrueString is "True" and Boolean.FalseString is "False" by default.

I know the reason why it is the way it is has already been addressed, but when it comes to "custom" boolean formatting, I've got two extension methods that I can't live without anymore :-)

public static class BoolExtensions
{
    public static string ToString(this bool? v, string trueString, string falseString, string nullString="Undefined") {
        return v == null ? nullString : v.Value ? trueString : falseString;
    }
    public static string ToString(this bool v, string trueString, string falseString) {
        return ToString(v, trueString, falseString, null);
    }
}

Usage is trivial. The following converts various bool values to their Portuguese representations:

string verdadeiro = true.ToString("verdadeiro", "falso");
string falso = false.ToString("verdadeiro", "falso");
bool? v = null;
string nulo = v.ToString("verdadeiro", "falso", "nulo");

It's simple code to convert that to all lower case.

Not so simple to convert "true" back to "True", however.

true.ToString().ToLower() 

is what I use for xml output.

...because the .NET environment is designed to support many languages.

System.Boolean (in mscorlib.dll) is designed to be used internally by languages to support a boolean datatype. C# uses all lowercase for its keywords, hence 'bool', 'true', and 'false'.

VB.NET however uses standard casing: hence 'Boolean', 'True', and 'False'.

Since the languages have to work together, you couldn't have true.ToString() (C#) giving a different result to True.ToString() (VB.NET). The CLR designers picked the standard CLR casing notation for the ToString() result.

The string representation of the boolean true is defined to be Boolean.TrueString.

(There's a similar case with System.String: C# presents it as the 'string' type).

For Xml you can use XmlConvert.ToString method.

How is it not compatible with C#? Boolean.Parse and Boolean.TryParse is case insensitive and the parsing is done by comparing the value to Boolean.TrueString or Boolean.FalseString which are "True" and "False".

EDIT: When looking at the Boolean.ToString method in reflector it turns out that the strings are hard coded so the ToString method is as follows:

public override string ToString()
{
    if (!this)
    {
        return "False";
    }
    return "True";
}

It's simple code to convert that to all lower case.

Not so simple to convert "true" back to "True", however.

true.ToString().ToLower() 

is what I use for xml output.

...because the .NET environment is designed to support many languages.

System.Boolean (in mscorlib.dll) is designed to be used internally by languages to support a boolean datatype. C# uses all lowercase for its keywords, hence 'bool', 'true', and 'false'.

VB.NET however uses standard casing: hence 'Boolean', 'True', and 'False'.

Since the languages have to work together, you couldn't have true.ToString() (C#) giving a different result to True.ToString() (VB.NET). The CLR designers picked the standard CLR casing notation for the ToString() result.

The string representation of the boolean true is defined to be Boolean.TrueString.

(There's a similar case with System.String: C# presents it as the 'string' type).

For Xml you can use XmlConvert.ToString method.

This probably harks from the old VB NOT .Net days when bool.ToString produced True or False.

How is it not compatible with C#? Boolean.Parse and Boolean.TryParse is case insensitive and the parsing is done by comparing the value to Boolean.TrueString or Boolean.FalseString which are "True" and "False".

EDIT: When looking at the Boolean.ToString method in reflector it turns out that the strings are hard coded so the ToString method is as follows:

public override string ToString()
{
    if (!this)
    {
        return "False";
    }
    return "True";
}

The reason true is "True" is because of Microsoft's strong bond with XML standards.

From Wikipedia: "Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format which is both human-readable and machine-readable."

Human-readable is subjective, but in the eyes of XML, using the word "One" in place of a number "1" is preferred. You'll notice this happens using enums, as the word gets serialized instead of its value ("FirstOption" instead of "0" or "1").

Likewise, text commonly follows CamelCasing. Therefore, instead of "string", XML prefers "String". This is why Boolean.TrueString is "True" and Boolean.FalseString is "False" by default.

I know the reason why it is the way it is has already been addressed, but when it comes to "custom" boolean formatting, I've got two extension methods that I can't live without anymore :-)

public static class BoolExtensions
{
    public static string ToString(this bool? v, string trueString, string falseString, string nullString="Undefined") {
        return v == null ? nullString : v.Value ? trueString : falseString;
    }
    public static string ToString(this bool v, string trueString, string falseString) {
        return ToString(v, trueString, falseString, null);
    }
}

Usage is trivial. The following converts various bool values to their Portuguese representations:

string verdadeiro = true.ToString("verdadeiro", "falso");
string falso = false.ToString("verdadeiro", "falso");
bool? v = null;
string nulo = v.ToString("verdadeiro", "falso", "nulo");

This probably harks from the old VB NOT .Net days when bool.ToString produced True or False.

How is it not compatible with C#? Boolean.Parse and Boolean.TryParse is case insensitive and the parsing is done by comparing the value to Boolean.TrueString or Boolean.FalseString which are "True" and "False".

EDIT: When looking at the Boolean.ToString method in reflector it turns out that the strings are hard coded so the ToString method is as follows:

public override string ToString()
{
    if (!this)
    {
        return "False";
    }
    return "True";
}

...because the .NET environment is designed to support many languages.

System.Boolean (in mscorlib.dll) is designed to be used internally by languages to support a boolean datatype. C# uses all lowercase for its keywords, hence 'bool', 'true', and 'false'.

VB.NET however uses standard casing: hence 'Boolean', 'True', and 'False'.

Since the languages have to work together, you couldn't have true.ToString() (C#) giving a different result to True.ToString() (VB.NET). The CLR designers picked the standard CLR casing notation for the ToString() result.

The string representation of the boolean true is defined to be Boolean.TrueString.

(There's a similar case with System.String: C# presents it as the 'string' type).

This probably harks from the old VB NOT .Net days when bool.ToString produced True or False.

For Xml you can use XmlConvert.ToString method.