How do I print the elements of a C vector in GDB

Question

I want to examine the contents of a std  vector in GDB  how do I do it   Let s say it s a std  vector lt int gt  for the sake of simplicity

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A little late to the party  so mostly a reminder to me next time I do this search    I have been able to use   p x    amp vec 2   4   to print 4 elements  as hex  from vec starting at vec 2

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A little late to the party  so mostly a reminder to me next time I do this search    I have been able to use   p x    amp vec 2   4   to print 4 elements  as hex  from vec starting at vec 2

User · Answer

put the following in    gdbinit  define print vector     if  argc    2         set  elem    arg0 size           if  arg1  gt    arg0 size               printf  Error   s size      d  printing last element  n     arg0    arg0 size               set  elem    arg1 -1         end         print    arg0  M impl  M start    elem  1     else         print    arg0  M impl  M start   arg0 size       end end  document print vector Display vector contents Usage  print vector VECTOR NAME INDEX VECTOR NAME is the name of the vector INDEX is an optional argument specifying the element to display end   After restarting gdb  or sourcing    gdbinit   show the associated help like this  gdb  help print vector Display vector contents Usage  print vector VECTOR NAME INDEX VECTOR NAME is the name of the vector INDEX is an optional argument specifying the element to display   Example usage    gdb  print vector videoconfig  entries 0  32     subChannelId   177   261   sourceId   0   000   hasH264PayloadInfo   false  bitrate   0      payloadType   68  D   maxFs   0  maxMbps   0  maxFps   134  encoder   0   000   temporalLayers   0   000

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With GCC 4 1 2  to print the whole of a std  vector lt int gt  called myVector  do the following   print   myVector  M impl  M start  myVector size     To print only the first N elements  do   print   myVector  M impl  M start  N   Explanation  This is probably heavily dependent on your compiler version  but for GCC 4 1 2  the pointer to the internal array is   myVector  M impl  M start    And the GDB command to print N elements of an array starting at pointer P is   print P N   Or  in a short form  for a standard  gdbinit    p P N

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With GCC 4 1 2  to print the whole of a std  vector lt int gt  called myVector  do the following   print   myVector  M impl  M start  myVector size     To print only the first N elements  do   print   myVector  M impl  M start  N   Explanation  This is probably heavily dependent on your compiler version  but for GCC 4 1 2  the pointer to the internal array is   myVector  M impl  M start    And the GDB command to print N elements of an array starting at pointer P is   print P N   Or  in a short form  for a standard  gdbinit    p P N

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With GCC 4 1 2  to print the whole of a std  vector lt int gt  called myVector  do the following   print   myVector  M impl  M start  myVector size     To print only the first N elements  do   print   myVector  M impl  M start  N   Explanation  This is probably heavily dependent on your compiler version  but for GCC 4 1 2  the pointer to the internal array is   myVector  M impl  M start    And the GDB command to print N elements of an array starting at pointer P is   print P N   Or  in a short form  for a standard  gdbinit    p P N

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Watching  STL containers while debugging is somewhat of a problem  Here are 3 different solutions I have used in the past  none of them is perfect   1  Use GDB scripts from http   clith com gdb stl utils  These scripts allow you to print the contents of almost all STL containers  The problem is that this does not work for nested containers like a stack of sets   2  Visual Studio 2005 has fantastic support for watching STL containers  This works for nested containers but this is for their implementation for STL only and does not work if you are putting a STL container in a Boost container   3  Write your own  print  function  or method  for the specific item you want to print while debugging and use  call  while in GDB to print the item  Note that if your print function is not being called anywhere in the code g   will do dead code elimination and the  print  function will not be found by GDB  you will get a message saying that the function is inlined   So compile with -fkeep-inline-functions

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To view vector std  vector myVector contents  just type in GDB    gdb  print myVector   This will produce an output similar to    1   std  vector of length 3  capacity 4    10  20  30    To achieve above  you need to have gdb 7  I tested it on gdb 7 01  and some python pretty-printer  Installation process of these is described on gdb wiki   What is more  after installing above  this works well with Eclipse C   debugger GUI  and any other IDE using GDB  as I think

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put the following in    gdbinit  define print vector     if  argc    2         set  elem    arg0 size           if  arg1  gt    arg0 size               printf  Error   s size      d  printing last element  n     arg0    arg0 size               set  elem    arg1 -1         end         print    arg0  M impl  M start    elem  1     else         print    arg0  M impl  M start   arg0 size       end end  document print vector Display vector contents Usage  print vector VECTOR NAME INDEX VECTOR NAME is the name of the vector INDEX is an optional argument specifying the element to display end   After restarting gdb  or sourcing    gdbinit   show the associated help like this  gdb  help print vector Display vector contents Usage  print vector VECTOR NAME INDEX VECTOR NAME is the name of the vector INDEX is an optional argument specifying the element to display   Example usage    gdb  print vector videoconfig  entries 0  32     subChannelId   177   261   sourceId   0   000   hasH264PayloadInfo   false  bitrate   0      payloadType   68  D   maxFs   0  maxMbps   0  maxFps   134  encoder   0   000   temporalLayers   0   000

User · Answer

To view vector std  vector myVector contents  just type in GDB    gdb  print myVector   This will produce an output similar to    1   std  vector of length 3  capacity 4    10  20  30    To achieve above  you need to have gdb 7  I tested it on gdb 7 01  and some python pretty-printer  Installation process of these is described on gdb wiki   What is more  after installing above  this works well with Eclipse C   debugger GUI  and any other IDE using GDB  as I think

User · Answer

With GCC 4 1 2  to print the whole of a std  vector lt int gt  called myVector  do the following   print   myVector  M impl  M start  myVector size     To print only the first N elements  do   print   myVector  M impl  M start  N   Explanation  This is probably heavily dependent on your compiler version  but for GCC 4 1 2  the pointer to the internal array is   myVector  M impl  M start    And the GDB command to print N elements of an array starting at pointer P is   print P N   Or  in a short form  for a standard  gdbinit    p P N

User · Answer

Watching  STL containers while debugging is somewhat of a problem  Here are 3 different solutions I have used in the past  none of them is perfect   1  Use GDB scripts from http   clith com gdb stl utils  These scripts allow you to print the contents of almost all STL containers  The problem is that this does not work for nested containers like a stack of sets   2  Visual Studio 2005 has fantastic support for watching STL containers  This works for nested containers but this is for their implementation for STL only and does not work if you are putting a STL container in a Boost container   3  Write your own  print  function  or method  for the specific item you want to print while debugging and use  call  while in GDB to print the item  Note that if your print function is not being called anywhere in the code g   will do dead code elimination and the  print  function will not be found by GDB  you will get a message saying that the function is inlined   So compile with -fkeep-inline-functions

[c++] How do I print the elements of a C++ vector in GDB?

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