Question: I'm sending xml to another program, which expects boolean flags as "yes" or "no", rather than "true" or "false".

I have a class defined like:

```
[XmlRoot()]
public class Foo {
    public bool Bar { get; set; }
}

```

When I serialize it, my output looks like this:

```
<Foo><Bar>true</Bar></Foo>

```

But I would like it to be this:

```
<Foo><Bar>yes</Bar></Foo>

```

Can I do this at the time of serialization? I would prefer not to have to resort to this:

```
[XmlRoot()]
public class Foo {
    [XmlIgnore()]
    public bool Bar { get; set; }

    [XmlElement("Bar")]
    public string BarXml { get { return (Bar) ? "yes" : "no"; } }
}

```

Note that I also want to be able to *deserialize* this data back again.

Answer: 
Ok, I've been looking into this some more. Here's what I've come up with:

```
// use this instead of a bool, and it will serialize to "yes" or "no"
// minimal example, not very robust
public struct YesNo : IXmlSerializable {

    // we're just wrapping a bool
    private bool Value;

    // allow implicit casts to/from bool
    public static implicit operator bool(YesNo yn) {
        return yn.Value;
    }
    public static implicit operator YesNo(bool b) {
        return new YesNo() {Value = b};
    }

    // implement IXmlSerializable
    public XmlSchema GetSchema() { return null; }
    public void ReadXml(XmlReader reader) {
        Value = (reader.ReadElementContentAsString() == "yes");
    }
    public void WriteXml(XmlWriter writer) {
        writer.WriteString((Value) ? "yes" : "no");
    }
}

```

Then I change my Foo class to this:

```
[XmlRoot()]
public class Foo {      
    public YesNo Bar { get; set; }
}

```

Note that because `YesNo` is implicitly castable to `bool` (and vice versa), you can still do this:

```
Foo foo = new Foo() { Bar = true; };
if ( foo.Bar ) {
   // ... etc

```

In other words, you can treat it like a bool.

And w00t! It serializes to this:

```
<Foo><Bar>yes</Bar></Foo>

```

It also deserializes correctly. 

There is probably some way to get my XmlSerializer to automatically cast any `bool`s it encounters to `YesNo`s as it goes - but I haven't found it yet. Anyone?
@Blorgbeard:
If you have more then one of these YesNo classes in an object class,
make sure to read the entire element.

```
public void ReadXml(XmlReader reader)
{
    string element = reader.ReadOuterXml();
    int startIndex = element.IndexOf('>') + 1;
    int length = element.LastIndexOf('<') - startIndex;

    string text = (element.Substring(startIndex, length).ToLowerInvariant();

    Value = (text == "yes");
}

```

Otherwise this might cause problems.

> 
> The ReadXml method must reconstitute your object using the information that was written by the WriteXml method.
> 
> 
> When this method is called, the reader is positioned at the start of the element that wraps the information for your type. That is, just
>  before the start tag that indicates the beginning of a serialized
>  object. When this method returns, it must have read the entire element
>  from beginning to end, including all of its contents. Unlike the
>  WriteXml method, the framework does not handle the wrapper element
>  automatically. Your implementation must do so. Failing to observe
>  these positioning rules may cause code to generate unexpected runtime
>  exceptions or corrupt data.
> 
> 
>