(gdb) run hello
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /Users/doug/langs/c/test hello
Breakpoi开发者_如何转开发nt 1, main (argc=2, argv=0xbffffa7c) at hw3b.c:14
14 if (argc != 2) {
(gdb) printf "%s", argv
??????(gdb)
I searched other questions on SO and I tried all the commands that I found but I keep getting ??? marks. Why is that?
argv
isn't a string, it's a char**
- a pointer to the first of possibly multiple C strings.
I think you're looking for:
print argv[0]
print argv[1]
...
Or if you want to use printf:
printf "%s\n", argv[0]
But there's really no reason to in such a simple case, since gdb does know how to print char*
strings.
Or, if you want to be fancy, this works:
print *argv@argc
The syntax FOO@NUM
tells it to print an array of NUM
elements starting at FOO
. And I have no idea why the dereferencing works, but it does - I guess gdb is just nice like that. Someone enlighten me?
精彩评论