gdb笔记

$ gcc -g -o test test.c        --加-g选项查看调试信息 $ gdb ./test

(gdb) l                    --用l(list)显示我们的源代码

1 #include <stdio.h>

2

3 int main()

4 {

5 int i=0;

6

7 scanf("%d",i);

8 printf("i=%d\n");

9 return 0;

10 }

(gdb) b 7              --用b(break)设置断点

Breakpoint 1 at 0x400543: file test1.c, line 7.

(gdb) r                  --用r(run)运行，直到断点处

Starting program: /home/etk/cpp/test1

Breakpoint 1, main () at test1.c:7

7 scanf("%d",i);

Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.80.el6_3.5.x86_64

(gdb) p i               --用p(print)打印变量i的值[看到没，这里i的值是0哦      

$1 = 0

(gdb) n                 --用n(next)执行下一步

1

Program received signal SIGSEGV, Segmentation fault.

0x004e3d45 in _IO_vfscanf_internal (s=0x31,

    format=0xffffffff <Address 0xffffffff out of bounds>, argptr=0x0,

    errp=0xb) at vfscanf.c:1772

1772 *ARG (unsigned int *) = (unsigned int) num.ul;

(gdb) c                 --用c(continue)继续执行

Program terminated with signal SIGSEGV, Segmentation fault.

The program no longer exists.

(gdb) q                --退出gdb