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| <h2 class="chapter">10 Examining Data</h2> |
| |
| <p><a name="index-printing-data-489"></a><a name="index-examining-data-490"></a><a name="index-print-491"></a><a name="index-inspect-492"></a><!-- "inspect" is not quite a synonym if you are using Epoch, which we do not --> |
| <!-- document because it is nonstandard... Under Epoch it displays in a --> |
| <!-- different window or something like that. --> |
| The usual way to examine data in your program is with the <code>print</code> |
| command (abbreviated <code>p</code>), or its synonym <code>inspect</code>. It |
| evaluates and prints the value of an expression of the language your |
| program is written in (see <a href="Languages.html#Languages">Using <span class="sc">gdb</span> with Different Languages</a>). It may also print the expression using a |
| Python-based pretty-printer (see <a href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>). |
| |
| <dl> |
| <dt><code>print </code><var>expr</var><dt><code>print /</code><var>f</var> <var>expr</var><dd><var>expr</var> is an expression (in the source language). By default the |
| value of <var>expr</var> is printed in a format appropriate to its data type; |
| you can choose a different format by specifying ‘<samp><span class="samp">/</span><var>f</var></samp>’, where |
| <var>f</var> is a letter specifying the format; see <a href="Output-Formats.html#Output-Formats">Output Formats</a>. |
| |
| <br><dt><code>print</code><dt><code>print /</code><var>f</var><dd><a name="index-reprint-the-last-value-493"></a>If you omit <var>expr</var>, <span class="sc">gdb</span> displays the last value again (from the |
| <dfn>value history</dfn>; see <a href="Value-History.html#Value-History">Value History</a>). This allows you to |
| conveniently inspect the same value in an alternative format. |
| </dl> |
| |
| <p>A more low-level way of examining data is with the <code>x</code> command. |
| It examines data in memory at a specified address and prints it in a |
| specified format. See <a href="Memory.html#Memory">Examining Memory</a>. |
| |
| <p>If you are interested in information about types, or about how the |
| fields of a struct or a class are declared, use the <code>ptype </code><var>exp</var> |
| command rather than <code>print</code>. See <a href="Symbols.html#Symbols">Examining the Symbol Table</a>. |
| |
| <ul class="menu"> |
| <li><a accesskey="1" href="Expressions.html#Expressions">Expressions</a>: Expressions |
| <li><a accesskey="2" href="Ambiguous-Expressions.html#Ambiguous-Expressions">Ambiguous Expressions</a>: Ambiguous Expressions |
| <li><a accesskey="3" href="Variables.html#Variables">Variables</a>: Program variables |
| <li><a accesskey="4" href="Arrays.html#Arrays">Arrays</a>: Artificial arrays |
| <li><a accesskey="5" href="Output-Formats.html#Output-Formats">Output Formats</a>: Output formats |
| <li><a accesskey="6" href="Memory.html#Memory">Memory</a>: Examining memory |
| <li><a accesskey="7" href="Auto-Display.html#Auto-Display">Auto Display</a>: Automatic display |
| <li><a accesskey="8" href="Print-Settings.html#Print-Settings">Print Settings</a>: Print settings |
| <li><a accesskey="9" href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>: Python pretty printing |
| <li><a href="Value-History.html#Value-History">Value History</a>: Value history |
| <li><a href="Convenience-Vars.html#Convenience-Vars">Convenience Vars</a>: Convenience variables |
| <li><a href="Registers.html#Registers">Registers</a>: Registers |
| <li><a href="Floating-Point-Hardware.html#Floating-Point-Hardware">Floating Point Hardware</a>: Floating point hardware |
| <li><a href="Vector-Unit.html#Vector-Unit">Vector Unit</a>: Vector Unit |
| <li><a href="OS-Information.html#OS-Information">OS Information</a>: Auxiliary data provided by operating system |
| <li><a href="Memory-Region-Attributes.html#Memory-Region-Attributes">Memory Region Attributes</a>: Memory region attributes |
| <li><a href="Dump_002fRestore-Files.html#Dump_002fRestore-Files">Dump/Restore Files</a>: Copy between memory and a file |
| <li><a href="Core-File-Generation.html#Core-File-Generation">Core File Generation</a>: Cause a program dump its core |
| <li><a href="Character-Sets.html#Character-Sets">Character Sets</a>: Debugging programs that use a different |
| character set than GDB does |
| <li><a href="Caching-Remote-Data.html#Caching-Remote-Data">Caching Remote Data</a>: Data caching for remote targets |
| <li><a href="Searching-Memory.html#Searching-Memory">Searching Memory</a>: Searching memory for a sequence of bytes |
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