确保你的程序有可调式的信息

使用gcc编译一个程序 ,带上一些额外的参数

-o0 -g

-o0 ：避免编译器优化，使用最低的优化等级，默认的编译选项
-g ：生产调试信息

如果你已经有一个工程demo，使用cmake时注意使用Debug模式，如:
SET(CMAKE_BUILD_TYPE "Debug")

调试一个简单的程序

示例代码
在这里插入图片描述
在130行出打断点，并读取变量值
gdb的调试记录如下：

root@1124ceb4e92e:/data/smc/Cool/build# gdb cool
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from cool...done.
(gdb) b 130
Breakpoint 1 at 0x40e8a0: file /data/smc/Cool/src/main.cpp, line 130.
(gdb) r
Starting program: /data/smc/Cool/build/cool
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff1bbc700 (LWP 3502)]
[New Thread 0x7fffef3bb700 (LWP 3503)]
[New Thread 0x7fffeebba700 (LWP 3504)]
[New Thread 0x7fffea3b9700 (LWP 3505)]
[New Thread 0x7fffe7bb8700 (LWP 3506)]
[New Thread 0x7fffe73b7700 (LWP 3507)]
[New Thread 0x7fffe4bb6700 (LWP 3508)]

Thread 1 "cool" hit Breakpoint 1, main (argc=1, argv=0x7ffffffa9518) at /data/smc/Cool/src/main.cpp:130
130             ++value_a;
(gdb) print value_a
$1 = 0
(gdb) c
Continuing.

Thread 1 "cool" hit Breakpoint 1, main (argc=1, argv=0x7ffffffa9518) at /data/smc/Cool/src/main.cpp:130
130             ++value_a;
(gdb) print value_a
$2 = 1
(gdb)