How to prevent buffer overflows?

[lucky6969b]

I have declared some local variables in various places inside a function.
I have checked the boundary checks option in the C++ option section.
But sometimes some local variables will get overwritten by previous variables,
so it becomes garbage. I don't know why, recently, this happens more often in the VS2010 compiler
I can't recall what options I have changed to the project properties.
How to prevent this problem from happening again?

// one set of bones per meshcontainer
DWORD nBones = meshcontainer->dwNumBones;

for (int iBone = 0; iBone < nBones; iBone++)

Like this code snippet, iBone is overflowed by nBones, and it becomes an extremely large value...
Thanks
Jack

[2kaud]

How to prevent this problem from happening again?

Write correct code! Basically you have a bug(s) in the code. c++ doesn't do bounds testing (except for some methods with containers) or memory checks etc. The compiler just assumes you know what you're doing and lets you do it and generates the code!

I don't know why, recently, this happens more often in the VS2010 compiler

Because you have changed some code! The symptoms may show more with one compiler than another because of the difference in how code is generated - but the underlying code problem is still present!

Having code/variables being overwritten unintentionally is a symptom of the code writing to areas of memory it which it shouldn't. Often if code is changed (even with some output statements for debugging) then the 'problem' can move. Common suspects include
exceeding the bounds of a stack based array (especially that the last element is 1 less than the number of elements)
for c-style strings not allocating an extra byte for the null terminator
not allocating sufficient memory for a dynamic array
freeing allocated memory and then still using the pointer
having a pointer variable that isn't initialised correctly
etc etc etc

In large code bases these sort of errors can be difficult to track down. Have you considered using a static code analyser?

[Arjay]

Lucky, as a side note, kind of wondering why you use VS 2010 and don't use VS 2015?

Care to post your reasons? If they are performance or usage related, I'd bet MS would like to here about them.