如何检查GDB中函数的返回值？
是否有可能在gdb中检查函数的返回值，假定返回值没有分配给variables？
我想有更好的办法做到这一点，但执行完成命令，直到当前的堆栈框架被popup并打印返回值 – 给定的程序
int fun() { return 42; } int main( int argc, char *v[] ) { fun(); return 0; } 你可以这样debugging它 –
(gdb) r Starting program: /usr/home/hark/a.out Breakpoint 1, fun () at test.c:2 2 return 42; (gdb) finish Run till exit from #0 fun () at test.c:2 main () at test.c:7 7 return 0; Value returned is $1 = 42 (gdb)
是的，只需inputprint $eax来检查EAX寄存器。 对于大多数函数，返回值都存储在该寄存器中，即使它没有被使用。
这个例外是函数返回大于32位的types，特别是64位整数（ long long ）， double s和structs或classes 。
另一个例外是，如果你没有在英特尔架构上运行。 在这种情况下，你必须找出使用哪个寄存器（如果有的话）。
这是没有符号的方法。
gdb ls This GDB was configured as "ppc64-yellowdog-linux-gnu"... (no debugging symbols found) Using host libthread_db library "/lib64/libthread_db.so.1". (gdb) break __libc_start_main Breakpoint 1 at 0x10013cb0 (gdb) r Starting program: /bin/ls (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) Breakpoint 1 at 0xfdfed3c (no debugging symbols found) [Thread debugging using libthread_db enabled] [New Thread 4160418656 (LWP 10650)] (no debugging symbols found) (no debugging symbols found) [Switching to Thread 4160418656 (LWP 10650)] Breakpoint 1, 0x0fdfed3c in __libc_start_main () from /lib/libc.so.6 (gdb) info frame Stack level 0, frame at 0xffd719a0: pc = 0xfdfed3c in __libc_start_main; saved pc 0x0 called by frame at 0x0 Arglist at 0xffd71970, args: Locals at 0xffd71970, Previous frame's sp is 0xffd719a0 Saved registers: r24 at 0xffd71980, r25 at 0xffd71984, r26 at 0xffd71988, r27 at 0xffd7198c, r28 at 0xffd71990, r29 at 0xffd71994, r30 at 0xffd71998, r31 at 0xffd7199c, pc at 0xffd719a4, lr at 0xffd719a4 (gdb) frame 0 #0 0x0fdfed3c in __libc_start_main () from /lib/libc.so.6 (gdb) info fr Stack level 0, frame at 0xffd719a0: pc = 0xfdfed3c in __libc_start_main; saved pc 0x0 called by frame at 0x0 Arglist at 0xffd71970, args: Locals at 0xffd71970, Previous frame's sp is 0xffd719a0 Saved registers: r24 at 0xffd71980, r25 at 0xffd71984, r26 at 0xffd71988, r27 at 0xffd7198c, r28 at 0xffd71990, r29 at 0xffd71994, r30 at 0xffd71998, r31 at 0xffd7199c, pc at 0xffd719a4, lr at 0xffd719a4
格式有点弄乱了，注意使用“信息框架”检查框架，“框架＃”导航您的上下文到另一个上下文（上下堆栈）
BT也显示了一个缩略的帮助。
