System
Fresh install of codeblocks 12.11 + mingw pack.
- win7 64
- gcc 4.7.1
- gdb 7.5
Example code
Compiled with -g and no optimization.
#include <stdio.h>
void foo(int a, int b);
int main() {
foo(400, 42);
return 0;
}
void foo(int a, int b) {
a = a - 10;
b = a + 1;
printf("y2 %d\n", b);
}
Problem
I put a breakpoint on "void foo(int a, int b)" and I look value of b as I step through the 3 lines. Either with the codeblocks debugging features or with the gdb command line, the value of b is 42 instead of being 391. The console output is correct, 391.
GDB commands
C:\DebugTest>"C:\Program Files (x86)\CodeBlocks\MinGW\bin\gdb.exe"
GNU gdb (GDB) 7.5
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-mingw32".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
(gdb) file bin/Debug/DebugTest.exe
Reading symbols from C:\DebugTest\bin\Debug\DebugTest.exe...done.
(gdb) break foo
Breakpoint 1 at 0x401363: file C:\DebugTest\main.c, line 14.
(gdb) run
Starting program: C:\DebugTest\bin\Debug\DebugTest.exe
[New Thread 3596.0x658]
Breakpoint 1, foo (a=400, b=42) at C:\DebugTest\main.c:14
14 a = a - 10;
(gdb) print b
$1 = 42
(gdb) step
15 b = a + 1;
(gdb) print b
$2 = 42
(gdb) step
17 printf("y2 %d\n", b);
(gdb) print b
$3 = 42
(gdb)
Remarks
- When the same operations are done without a function, with a and b as local variables inside main, the debug output is correct.
- When compiled with gcc 4.4.1, the debug output is correct.
Any idea what could be wrong ? =)
bin gdb after assignmentb = a + 1;? – ks1322step inside foo?break foo,runthenprint b? – Davide Berrab = a + 1line. @DavideBerra I put a breakpoint on thevoid foo(int a, int b) {using codeblocks, I don't use gdb command except print. Updated the post. – Teybeo