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<concept xml:lang="en" id="GUID-82762D6D-7EF5-5061-9393-BBDCCC7212CD"><title>Using TCardinality</title><prolog><metadata><keywords/></metadata></prolog><conbody><p><codeph>TCardinality</codeph>'s use is best explained by an example:</p> <p>If an integral value that needs externalising is known to be non-negative and cannot exceed 2^29 (e.g. the length of a descriptor) - instead of storing a 32-bit value in the stream, you can use <codeph>TCardinality</codeph> to compress the external format. So instead of</p> <codeblock id="GUID-7B78C47F-C8A2-5C64-9551-BDA725407B34" xml:space="preserve">writeStream.WriteUint32L(myValue);

...

myValue=readStream.ReadUint32L();</codeblock> <p>you would use</p> <codeblock id="GUID-5C11D583-E2E5-5891-BC0D-2BD74193889D" xml:space="preserve">writeStream &lt;&lt; TCardinality(myValue);

...

TCardinality c;

readStream >> c;