#include <windows.h>
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
int a, b;
b = a;
return 0;
}
Unusual compiler behaviour.
Author
A very wierd situation.
This program compiles under VC++7, but crashes on execution.
All the program does is move an uninitialised variable from a to b. AFAIK this is, while bad practice, legal and easily acheivable (?spellig).
Note, the program could be optimised to just do nothing but return 0.
Is this a compiler bug? Can anyone explain this?
Compiler: MSVC++ 7. (Default debug build).
OS: Windows XP SP1.
Architecture: Standard x86.
Running it in the debugger whould cause both values to be initialized to a default value by the debugger.
CHeers
Chris
CHeers
Chris
Quote:------ Build started: Project: test, Configuration: Debug Win32 ------Compiling...test.cpp<path name>\test.cpp(5) : warning C4700: local variable 'a' used without having been initializedLinking...Build Time 0:16Build log was saved at "file://<path name>\Debug\BuildLog.htm"test - 0 error(s), 1 warning(s)---------------------- Done ---------------------- Build: 1 succeeded, 0 failed, 0 skipped
No Probs here.
How do you know the program crashed at runtime? All it should do is start a process for a split second and close - there shouldn't even be any windows to open. If you're compiling with the console option on, you would see a console flash on the screen for a second but that would be it. Are you getting some kind of error message?
Author
To chollida1 / Anon Mike: Yep, running it under the debugger makes it proceed without a crash.
To ZedFx: It compiles fine for me also, with the warning. It's when I run it that I get the crash.
I actually found this when I was running a simple test program on data types, where some of the types didn't exist so my switch/case did not do the test for them and therefore didn't write the data to the variables that were printed afterwards. I simplified the program right down to the code I posted and got the same problem.
Odd.
To ZedFx: It compiles fine for me also, with the warning. It's when I run it that I get the crash.
I actually found this when I was running a simple test program on data types, where some of the types didn't exist so my switch/case did not do the test for them and therefore didn't write the data to the variables that were printed afterwards. I simplified the program right down to the code I posted and got the same problem.
Odd.
Author
To TheBluMage:
It's compiled under standard Win32 App, not console.
I get the typical windows error:
"TypesTest has encountered a serious error and needs to close, blah blah etc".
When I run the generated executable. If I remove the offending "b = a;" then then program completes without error.
It's compiled under standard Win32 App, not console.
I get the typical windows error:
"TypesTest has encountered a serious error and needs to close, blah blah etc".
When I run the generated executable. If I remove the offending "b = a;" then then program completes without error.
Ok I actually built it inside VC this time instead of using the command line. Is this what you mean by "crash"?:
If so that's not a crash, it's a debugging feature.
If that's not the problem what *exactly* are you seeing?
**edit**
Ok just read the above message. I suspect you are linking with the wrong c runtime dlls or something and the above debug spew is going off into never-never land.
Quote:
---------------------------
Microsoft Visual C++ Debug Library
---------------------------
Debug Error!
Program: D:\Projects\GUITest\Debug\guitest.exe
Module: D:\Projects\GUITest\Debug\guitest.exe
File: d:\projects\guitest\guitest.cpp
Line: 5
Run-Time Check Failure #3 - The variable 'a' is being used without being defined.
(Press Retry to debug the application)
---------------------------
Abort Retry Ignore
---------------------------
If so that's not a crash, it's a debugging feature.
If that's not the problem what *exactly* are you seeing?
**edit**
Ok just read the above message. I suspect you are linking with the wrong c runtime dlls or something and the above debug spew is going off into never-never land.
Regarding the message written by Anon Mike
should do it, I always initialise my variables, because this runtime error is a pain.
#include <windows.h>int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { int a, b = 0; b = a; return 0;}should do it, I always initialise my variables, because this runtime error is a pain.
Quote:Original post by ZedFx
Regarding the message written by Anon Mike
*** Source Snippet Removed ***
should do it, I always initialise my variables, because this runtime error is a pain.
In that code 'a' remains uninitialised. [razz]
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
