> For the complete documentation index, see [llms.txt](https://alex-robenko.gitbook.io/commsdsl-specification/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alex-robenko.gitbook.io/commsdsl-specification/fields/string.md).

# string Field

This field stores and abstracts away value of a text string. The **\<string>** field has all the [common](/commsdsl-specification/fields/common.md) properties as well as extra properties and elements described below.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <string name="SomeStringField" />
    </fields>
</schema>
```

Such definition of the **\<string>** does **NOT** have any limit on the length of the string, and will consume all the available data in the input buffer.

## Default Value

The default value of the **\<string>** field when constructed can be specified using **defaultValue** [property](/commsdsl-specification/properties.md). If not specified, defaults to empty string.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <string name="SomeStringField" defaultValue="hello" />
    </fields>
</schema>
```

## Fixed Length

In case the string value needs to be serialized using predefined fixed length, use **length** property to specify the required value.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <string name="SomeStringField" length="16" />
    </fields>
</schema>
```

## Length Prefix

Many protocols prefix string with its length. The **CommsDSL** allows definition of such prefix using **lengthPrefix** child element, which must define prefix as [\<int>](/commsdsl-specification/fields/int.md) field.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <string name="SomeStringField">
            <lengthPrefix>
                <int name="LengthPrefix" type="uint8" />
            </lengthPrefix>
        <string>
    </fields>
</schema>
```

In case the prefix field is defined as external field, **CommsDSL** allows usage of **lengthPrefix** as [property](/commsdsl-specification/properties.md), value of which contains name of the referenced field.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <int name="StringLengthPrefix" type="uint8" />
        <string name="SomeStringField" lengthPrefix="StringLengthPrefix" />
    </fields>
</schema>
```

The **CommsDSL** also supports **detached** length prefix, when there are several other fields in the [\<message>](/commsdsl-specification/messages.md) or in the [\<bundle>](/commsdsl-specification/fields/bundle.md) between the length field and the **\<string>**.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <bundle name=SomeBundle">
            <int name="StringLengthPrefixMember" type="uint8" />
            <int name="SomeOtherFieldMember" type="uint8" />
            <string name="SomeStringFieldMember" lengthPrefix="$StringLengthPrefixMember" />
        </bundle>
    </fields>

    <message name="Msg1" id="1">
        <int name="StringLengthPrefix" type="uint8" />
        <int name="SomeOtherField" type="uint8" />
        <string name="SomeStringField" lengthPrefix="$StringLengthPrefix" />
    </message>
</schema>
```

**NOTE**, the existence of **$** prefix when specifying **lengthPrefix** value. It indicates that the referenced field is a sibling in the containing [\<message>](/commsdsl-specification/messages.md) or the [\<bundle>](/commsdsl-specification/fields/bundle.md) field.

The code generator is expected to take the existence of such detached prefix into account and generate correct code for various field operations (read, write, etc...).

## Zero Termination Suffix

Some protocols may terminate strings with **0** (zero) byte. The **CommsDSL** support such cases with existence of **zeroTermSuffix** [property](/commsdsl-specification/properties.md) with [boolean](/commsdsl-specification/boolean.md) value.

```
<?xml version="1.0" encoding="UTF-8"?>
<schema ...>
    <fields>
        <string name="SomeStringField" zeroTermSuffix="true" />
    </fields>
</schema>
```

**NOTE**, that **length**, **lengthPrefix** and **zeroTermSuffix** properties are mutually exclusive, i.e. cannot be used together.

Use [properties table](/commsdsl-specification/appendix/string.md) for future references.