gdb跳出函数

1. return

   • 说明

     • 从当前指令直接返回,即不执行后续指令.

   • 案例分析

     chen@chen:~/cppfile/test$ gdb -q ./a.out
     Reading symbols from ./a.out...done.
     (gdb) b show
     Breakpoint 1 at 0x4004d6: file test.cpp, line 3.
     (gdb) r
     Starting program: /home/chen/cppfile/test/a.out
     
     Breakpoint 1, show () at test.cpp:3
     3           test = 1;
     (gdb) p test
     $1 = 0
     (gdb) return
     Make show() return now? (y or n) y
     #0  main () at test.cpp:7
     7       }
     (gdb) p test
     $2 = 0
     (gdb) !cat test.cpp
     int test = 0;
     void show() {
        test = 1;
     }
     int main() {
        show();
     }
     

     • 可以看到直接退出，没有执行test=1,正常执行完，test的值应该是为1的。

2. finish | fin

   • 简介

     • 执行完当前函数后停止，即到上一层，函数调用的地方停止。

     • 类比step out.

   • 案例

     chen@chen:~/cppfile/test$ gdb -q ./a.out
     Reading symbols from ./a.out...done.
     (gdb) b show
     Breakpoint 1 at 0x4004d6: file test.cpp, line 3.
     (gdb) r
     Starting program: /home/chen/cppfile/test/a.out
     
     Breakpoint 1, show () at test.cpp:3
     3           test = 1;
     (gdb) bt
     #0  show () at test.cpp:3
     #1  0x00000000004004f6 in main () at test.cpp:7
     (gdb) finish
     Run till exit from #0  show () at test.cpp:3
     main () at test.cpp:8
     8       }
     (gdb) p test
     $1 = 2
     (gdb) !cat test.cpp
     int test = 0;
     void show() {
        test = 1;
        test = 2;
     }
     int main() {
        show();
     }
     

     • 可以看到和return的差异。