Print C++ vtables using GDB

I'm trying to print an object's vtable using gdb; I found the

show print vt bl on

setting, but I still don't actually know how to print the vtable - p *开发者_运维百科object still doesn't print it out.

How do I print the vtable?

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A more compact solution:

p /a (*(void ***)obj)[0]@10

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If you have a sufficiently new version of gdb, you may want to look at the "info vtbl" command.

I only noticed the feature when googling for an answer to this question and I noticed posts to the gdb mailing list circa 2012, notably this one from March 2012:

http://permalink.gmane.org/gmane.comp.gdb.patches/73957

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  (gdb) set $i = 0
  (gdb) while $i < 10
     >print $i
     >p /a (*(void ***)obj)[$i]
     >set $i = $i + 1
     >end

Where "obj" is the object whose vtable you'd like to print, and 10 is the number of methods.

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In the actual gdb 7.5.1 the command is not info vtable!

Use info vtbl

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For the example at http://en.cppreference.com/w/cpp/language/virtual

Without using 'info vtbl'

(gdb) p b
$1 = {_vptr.Base = 0x400a60 <vtable for Base+16>}

(gdb) x/16x 0x400a60
0x400a60 <_ZTV4Base+16>:    0x0040094c  0x00000000  0x72654437  0x64657669

(gdb) x/16x 0x0040094c
0x40094c <Base::f()>:   0xe5894855  0x10ec8348  0xf87d8948  0x400a15be
0x40095c <Base::f()+16>:    0x10c0bf00  0xf9e80060  0xc9fffffd  0x485590c3
0x40096c <Derived::f()+2>:  0x8348e589  0x894810ec  0x1bbef87d  0xbf00400a
0x40097c <Derived::f()+18>: 0x006010c0  0xfffddbe8  0x66c3c9ff  0x00841f0f