https://community.cloudera.com/t5/Archives-of-Support-Questions/Why-HexaDecimal-String-of-any-VIntWritable-has-8f-at-the/m-p/29777#M6653 The first byte value is used as the sign indicator, if the number requires more than one byte to encode with.<BR /><BR />In your specific example with 172 and -172,<BR />1000|1111, or 8f, is used to indicate positive numbers<BR />1000|0111, or 87, is used to indicate negative numbers<BR /><BR />It helps also if you look at the sources to answer such questions, i.e. at <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L271-L298" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L271-L298</A> (serialise) and <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L307-L320" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L307-L320</A> (deserialise). Also look at this: <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L369-L371" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L369-L371</A><BR /><BR />Does this help? Sun, 19 Jul 2015 11:43:32 GMT Harsh J 2015-07-19T11:43:32Z https://community.cloudera.com/t5/Archives-of-Support-Questions/Why-HexaDecimal-String-of-any-VIntWritable-has-8f-at-the/m-p/29774#M6652 <P>I am checking some concepts in Definitive guide and could not figure out this small logic.</P><P>&nbsp;</P><P>When you convert VIntWritable to Byte Array and convert that byte array to string, there is additional '8f' at the start of any avalue.</P><P>&nbsp;</P><P>for eg:</P><P>&nbsp;</P><P>for normal IntWritable the value of 172 in hexa decimal representation is - 000000ac</P><P>for VIntWritable, the HexaDecimal String for 172&nbsp; is&nbsp; <STRONG>8f</STRONG>ac</P><P>for VIntWritable, the HexaDecimal String for -172 is&nbsp; 87ab</P><P>&nbsp;</P><P>I am confused. could you please elaborate a bit.?</P> Sun, 19 Jul 2015 10:38:49 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/Why-HexaDecimal-String-of-any-VIntWritable-has-8f-at-the/m-p/29774#M6652 Srini_D 2015-07-19T10:38:49Z https://community.cloudera.com/t5/Archives-of-Support-Questions/Why-HexaDecimal-String-of-any-VIntWritable-has-8f-at-the/m-p/29777#M6653 The first byte value is used as the sign indicator, if the number requires more than one byte to encode with.<BR /><BR />In your specific example with 172 and -172,<BR />1000|1111, or 8f, is used to indicate positive numbers<BR />1000|0111, or 87, is used to indicate negative numbers<BR /><BR />It helps also if you look at the sources to answer such questions, i.e. at <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L271-L298" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L271-L298</A> (serialise) and <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L307-L320" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L307-L320</A> (deserialise). Also look at this: <A href="https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L369-L371" target="_blank">https://github.com/cloudera/hadoop-common/blob/cdh5.4.0-release/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L369-L371</A><BR /><BR />Does this help? Sun, 19 Jul 2015 11:43:32 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/Why-HexaDecimal-String-of-any-VIntWritable-has-8f-at-the/m-p/29777#M6653 Harsh J 2015-07-19T11:43:32Z