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<title>Debugging with GDB: Value Sizes</title>
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<a name="Value-Sizes"></a>
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Previous: <a href="Searching-Memory.html#Searching-Memory" accesskey="p" rel="previous">Searching Memory</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Value-Sizes-1"></a>
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<h3 class="section">10.23 Value Sizes</h3>
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<p>Whenever <small>GDB</small> prints a value memory will be allocated within
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<small>GDB</small> to hold the contents of the value. It is possible in
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some languages with dynamic typing systems, that an invalid program
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may indicate a value that is incorrectly large, this in turn may cause
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<small>GDB</small> to try and allocate an overly large amount of memory.
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</p>
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<dl compact="compact">
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<dd><a name="index-set-max_002dvalue_002dsize"></a>
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</dd>
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<dt><code>set max-value-size <var>bytes</var></code></dt>
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<dt><code>set max-value-size unlimited</code></dt>
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<dd><p>Set the maximum size of memory that <small>GDB</small> will allocate for the
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contents of a value to <var>bytes</var>, trying to display a value that
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requires more memory than that will result in an error.
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</p>
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<p>Setting this variable does not effect values that have already been
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allocated within <small>GDB</small>, only future allocations.
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</p>
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<p>There’s a minimum size that <code>max-value-size</code> can be set to in
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order that <small>GDB</small> can still operate correctly, this minimum is
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currently 16 bytes.
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</p>
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<p>The limit applies to the results of some subexpressions as well as to
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complete expressions. For example, an expression denoting a simple
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integer component, such as <code>x.y.z</code>, may fail if the size of
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<var>x.y</var> is dynamic and exceeds <var>bytes</var>. On the other hand,
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<small>GDB</small> is sometimes clever; the expression <code>A[i]</code>, where
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<var>A</var> is an array variable with non-constant size, will generally
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succeed regardless of the bounds on <var>A</var>, as long as the component
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size is less than <var>bytes</var>.
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</p>
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<p>The default value of <code>max-value-size</code> is currently 64k.
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</p>
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<a name="index-show-max_002dvalue_002dsize"></a>
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</dd>
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<dt><code>show max-value-size</code></dt>
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<dd><p>Show the maximum size of memory, in bytes, that <small>GDB</small> will
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allocate for the contents of a value.
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</p></dd>
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</dl>
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