Possible to automatically print out variables of source line on next in gdb? - Stack Overflow

admin管理员组

文章数量:1406913

Say I have a session like this in gdb:

320   mystruct.ticks++;
(gdb) n
321   mystruct.prev_state = mystruct.state;
(gdb) n
325   if( mystruct.variant == VARIANT_ONE )
(gdb) n
335     if( mystruct.prev_state == 0 )
(gdb) n
337       mystruct.state = 1;
(gdb) n
338       mystruct.state_final = mystruct.state;

Is it somehow possible to set up automatic printout of variables on the source line being executed after next is ran? It would look like this, dor instance:

320   mystruct.ticks++;
(gdb) n
mystruct.ticks = 102643

So, the only variable mentioned in line 320 is mystruct.ticks, and therefore after we press n and that line is executed, its value is automatically printed afterwards; then we get the next source line:

321   mystruct.prev_state = mystruct.state;
(gdb) n
mystruct.prev_state = 1
mystruct.state = 1

On this line, there are 2 variables used: mystruct.prev_state and mystruct.state - after next is executed, both of them are printed out by our imaginary functionality - and the printout confirms they are equal in value, as they should be.

Is it possible to somehow set up this kind of printout in gdb?

Say I have a session like this in gdb:

320   mystruct.ticks++;
(gdb) n
321   mystruct.prev_state = mystruct.state;
(gdb) n
325   if( mystruct.variant == VARIANT_ONE )
(gdb) n
335     if( mystruct.prev_state == 0 )
(gdb) n
337       mystruct.state = 1;
(gdb) n
338       mystruct.state_final = mystruct.state;

Is it somehow possible to set up automatic printout of variables on the source line being executed after next is ran? It would look like this, dor instance:

320   mystruct.ticks++;
(gdb) n
mystruct.ticks = 102643

So, the only variable mentioned in line 320 is mystruct.ticks, and therefore after we press n and that line is executed, its value is automatically printed afterwards; then we get the next source line:

321   mystruct.prev_state = mystruct.state;
(gdb) n
mystruct.prev_state = 1
mystruct.state = 1

On this line, there are 2 variables used: mystruct.prev_state and mystruct.state - after next is executed, both of them are printed out by our imaginary functionality - and the printout confirms they are equal in value, as they should be.

Is it possible to somehow set up this kind of printout in gdb?

• gdb

Share Improve this question Follow asked Mar 6 at 10:29 sdbbssdbbs 5,60477 gold badges5858 silver badges122122 bronze badges

Add a comment  | 

1 Answer 1

Sorted by: Reset to default 0

Have you checked out the display command ?
Edit: sorry, I read the question wrong and have no answer to address it.

[ranga@garuda gdb]$ cat 1.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main (int argc, char *argv[]) {
  struct {
    int argc;
    char **argv;
  } args = { argc, argv };
  argv[argc-1] = "last";
  return argc;
}
[ranga@garuda gdb]$ cc -g 1.c
[ranga@garuda gdb]$ gdb -q a.out
Reading symbols from /home/ranga/lrn/gdb/a.out...done.
(gdb) list
1       #include <stdio.h>
2       #include <stdlib.h>
3       #include <string.h>
4
5       int main (int argc, char *argv[]) {
6         struct {
7           int argc;
8           char **argv;
9         } args = { argc, argv };
10        argv[argc-1] = "last";
(gdb) break 9
Breakpoint 1 at 0x4004f8: file 1.c, line 9.
(gdb) r
Starting program: /home/ranga/lrn/gdb/a.out

Breakpoint 1, main (argc=1, argv=0x7fffffffdcb8) at 1.c:9
9         } args = { argc, argv };
Missing separate debuginfos, use: debuginfo-install glibc-2.17-326.el7_9.x86_64
(gdb) display args.argc
1: args.argc = -9040
(gdb) display args.argv[0]
2: args.argv[0] = <error: Cannot access memory at address 0x0>
(gdb) n
10        argv[argc-1] = "last";
2: args.argv[0] = 0x7fffffffdf5e "/home/ranga/lrn/gdb/a.out"
1: args.argc = 1
(gdb)
11        return argc;
2: args.argv[0] = 0x4005c0 "last"
1: args.argc = 1
(gdb)

本文标签： Possible to automatically print out variables of source line on next in gdbStack Overflow