- 论坛徽章:
- 2
|
一个非常简单的main函数,里面包含一个循环,如下所示:
- #include<stdio.h>
- int main()
- {
- for(int i=0;i<30;++i)
- printf("%d\n",i);
- return 0;
- }
复制代码
编译这个程序,带上调试信息:
生成a.out,然后来调试它,断点设置在第5,6这两行:
- $ gdb a.out
- GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04)...
- Reading symbols from a.out...done.
- (gdb) list
- 1 #include<stdio.h>
- 2 int main()
- 3 {
- 4 for(int i=0;i<30;++i)
- 5 printf("%d\n",i);
- 6 return 0;
- 7 }
- (gdb) b 5
- Breakpoint 1 at 0x400537: file 4.c, line 5.
- (gdb) b 6
- Breakpoint 2 at 0x400555: file 4.c, line 6.
- (gdb) r
- Starting program: /home/a/cpp/a.out
- Breakpoint 1, main () at 4.c:5
- 5 printf("%d\n",i);
- (gdb) p i
- $1 = 0
- (gdb) u
- 0
- 4 for(int i=0;i<30;++i)
- (gdb) u
- Breakpoint 1, main () at 4.c:5
- 5 printf("%d\n",i);
- (gdb)
- 1
- 4 for(int i=0;i<30;++i)
- (gdb) u
复制代码
看起来u命令并没有帮我退出for循环,为什么呢?
|
|