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devel / Programming / (C++) My gdb went wrong

(C++) My gdb went wrong

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From: Anonymous@news.novabbs.org (Anonymous)
Newsgroups: rocksolid.programming
Subject: (C++) My gdb went wrong
Date: Tue, 4 Jan 2022 16:15:33 +0000
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by: Anonymous - Tue, 4 Jan 2022 16:15 UTC

In the following code line 7, q[0] should be 1, but gdb claim that q[0] = 0. Can you plz explain what happened? It's GNU gdb (GDB) 11.1

(gdb) list
1 #include <cstdio>
2 #include <deque>
3
4 int main() {
5 std::deque<int> q;
6 q.push_front(1);
7 printf("%dn", q[0]);
8 return 0;
9 }
(gdb) b 7
Breakpoint 1 at 0x1227: file /tmp/a.cpp, line 7.
(gdb) r
Starting program: /tmp/a

Breakpoint 1, main () at /tmp/a.cpp:7
7 printf("%dn", q[0]);
(gdb) p q[0]
$1 = 0
(gdb) n
1 8 return 0;
quit)
A debugging session is active.

Inferior 1 [process 115399] will be killed.

Quit anyway? (y or n) y

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