gdb调试程序
Linux 包含了一个叫 gdb 的 GNU 调试程序. gdb 是一个用来调试 C 和 C++ 程序的强力调试器. 它使你能在程序运行时观察程序的内部结构和内存的使用情况. 以下是 gdb 所提供的一些功能:
- 它使你能监视你程序中变量的值.
- 它使你能设置断点以使程序在指定的代码行上停止执行.
- 它使你能一行行的执行你的代码.
以下演示一个example.c程序的调试过程：example.c文件内容如下，
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<string.h>
4
5 void my_print1(char *string);
6 void my_print2(char *string);
7
8 main()
9 {
10 char my_string[] = "hello there";
11 my_print1(my_string);
12 my_print2(my_string);
13 }
14
15 void my_print1(char *string)
16 {
17 printf ("The string is %s\n", string);
18 }
19
20 void my_print2(char *string)
21 {
22 char *string2;
23 int size, i;
24
25 size = strlen (string);
26 string2 = (char *) malloc (size + 1);
27
28 for (i = 0; i < size; i++)
29 string2[size - i] = string[i];
30
31 string2[size+1] = '\0';
32
33 printf ("The string printed backward is %s\n", string2);
34 }
1.编译时，打开-g选项编译程序，编译后的可执行程序包括调试信息（备注：-E 预处理，生成.i文件；-S 编译，生成.s文件； -c 汇编，生成.o目标文件）
lxw@RD004:~/test/dir_example$ gcc -g example.c -o example
lxw@RD004:~/test/dir_example$ gdb
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 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".
For bug reporting instructions, please see:
http://www.gnu.org/software/gdb/bugs/.
2.通过file命令加载可执行文件：
(gdb) file example
Reading symbols from /home/lxw/test/dir_example/example...done.
3.通过run命令执行
(gdb)run
Starting program: /home/lxw/test/dir_example/example
The string is hello there
The string printed backward is
Program exited with code 040.
程序异常退出。
４.(gdb) list
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<string.h>
4
5 void my_print1(char *string);
6 void my_print2 (char *string);
7
8 main()
9 {
10 char my_string[] = "hello there";
每次显示十行代码，再次输入list将显示后十行。
５.(gdb) break 29
Breakpoint 1 at 0x4006ad: file example.c, line 29.
设置断点在２９行
６.(gdb) next
Breakpoint 1, my_print2 (string=0x7fffffffe2e0 "hello there") at example.c:29
29 string2[size - i] = string[i];
单步运行，类似命令step. (简化命令 n)
7.(gdb) continue
Continuing.
Breakpoint 1, my_print2 (string=0x7fffffffe2e0 "hello there") at example.c:29
29 string2[size - i] = string[i];
继续往下执行 (简化命令 c)
８.(gdb) print i
$3 = 3
打印变量i的值（简化命令 p）
9.(gdb) info break
Num Type Disp Enb Address What
1 breakpoint keep y 0x00000000004006ad in my_print2 at example.c:29
breakpoint already hit 4 times
查看所有断点信息
１０.(gdb) help commandname
查看对应commandname的使用方法，如help breakpoints
11.(gdb) quit
退出gdb高度程序
以上为简单的GDB调试程序例子，详细见gdb帮助文档，附上一篇介绍不错的文章地址，作为收藏[http://dsec.pku.edu.cn/~yuhj/wiki/gdb.html]
