GDB：我怎样才能获得所有局部变量的名称？

Question

Is there a way in gdb to get the name of all local variables ? I know that

info local

prints names and values of local variables, but I would like to automatically compare the value of all the locals at several points of execution of a function (and there is a huge number of local variables in this function, so doing it manually one by one would be tedious ...)

Thanks !

Answer 1

It sounds like you really want a way to compare some locals at two points in time. There are a couple of ways to do this.

One low-tech way is to dump the variables with info locals . You can dump them to a file using the set logging facility, and you can completely automate this by setting a breakpoint whose commands do the logging, the dumping, disable the logging, and finally end with continue .

In this approach you would write a separate script to compare the results.

Another approach is to use gdb's Python scripting facility. It's easy to get the local variables here: get the selected frame with gdb.selected_frame() ; then get the frame's block ( frame.block() ); then iterate over the locals of the block to get that block's variables, and walk up the blocks (see gdb.Block.superblock ) until you reach the function boundary.

You can either evaluate or ignore symbols you find (if, say, you only want to compare some subset). And, you can decide how you want to compare the values you collect.

In this approach all the work is done in gdb, without any separate comparison script.