OctalLiteral.qhelp

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  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>


<overview>
<p>An integer literal consisting of a leading <code>0</code> digit
followed by one or more digits in the range <code>0-7</code> is an
octal literal. This can lead to two problems:</p>

<ul>
    <li>An octal literal can be misread by a programmer as a decimal literal.</li>
    <li>A programmer might accidentally start a decimal literal with a zero, so that the compiler
    treats the decimal literal as an octal literal. For example, <code>010</code> is equal to 
    <code>8</code>, not <code>10</code>.</li>
</ul>
 
</overview>
<recommendation>

<p>To avoid these problems:</p>

<ul>
    <li>Avoid using octal literals so that programmers do not confuse them with decimal literals. 
    However, if you need to use octal literals, you should add a comment to each octal literal 
    indicating the intention to use octal literals.</li>
    <li>When typing decimal literals, be careful not to begin them with a zero accidentally.</li>
</ul>

</recommendation>
<references>


<li>
  J. Bloch and N. Gafter, <em>Java Puzzlers: Traps, Pitfalls, and Corner Cases</em>, Puzzle 59. Addison-Wesley, 2005.
</li>
<li>
  Java Language Specification:
  <a href="https://docs.oracle.com/javase/specs/jls/se11/html/jls-3.html#jls-3.10.1">Integer Literals</a>.
</li>


</references>
</qhelp>