cl c++ runtime error while reading inaccessible memory - c++

Question

I have some c++ code but I don't know what. For the purposes of example let's say it is:
//main.cpp
#include<iostream>
using namespace std;
int T[100];
int main()
{
for(int i = 0; i < 100; ++i)
T[i] = i;
int x;
cin>>x;
cout<<T[x]<<endl;
return 0;
}
I'm compiling it by cl /O2 /nologo /EHsc main.cpp and running by main < inFile.in. Let's say that inFile.in content is one number 500 and new line. The output is some random number because program reads memory under the address T+500 and printing it.
I want to get runtime error in such cases (any possibility of checking is something like this happened). Is this possible without access to main.cpp?
To be specific I'm running all this programmatically by Process class in C# in ASP.Net MVC Application. I want to check did program threw exception / read not reserved memory etc.

Answer 1

Is this a feature you want to use for development purposes only, or also in your production environment?
In case of development purposes only you may try to run your application under some tool for runtime checking (like Valgrind/Dr Memory), or change the way you compile it to include runtime debug checks (is not guaranteed to work in described case, but helps in many others). Keep in mind that this will make your application much slower (thus should be used only for applications under development)
When it comes to production environment, I am not aware of any way of doing what you want to - in general you can only count on OS segmentation fault in case of reading out of available memory (if you have luck - if you don't it'll "work").
For the exception thing, I'm not 100% sure I understand what you mean - is this "why did the program terminate" ? In such case on you might get a core dump of crashed application (in case of normal termination I assume you have return codes), and you can inspect it later to either get crash reason or possibly also try to recover some data. For instructions how to collect dumps on Windows, you may check out:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb787181%28v=vs.85%29.aspx
However, this is also a feature that is more useful in development environment than in production.

Answer 2

If You can't modify above program's source then run it in 'outside' environment (shell) and get returned value and test it against 0 - any other value would me incorrect behavior.
It is also good to verify such programs' input data that you know it can't handle so rather than waiting for it to crash you can prevent it from happening.
If You could modify program then simple solution would be to use std::vector or std::deque which are similar but important is to use at() method and not the operator[] operator as the at() method checks bounds
#include<iostream>
#include<vector>
using namespace std;
std::vector<int> T(100);
int main()
{
for(int i = 0; i < 100; ++i)
T[i] = i;
int x;
cin>>x;
cout<<T.at(x)<<endl;
return 0;
}
if at() will be called with bad out-of-bound parameter then exception will be throw which You can catch like this:
try{
cin>>x;
cout<<T.at(x)<<endl;
}
catch(...)
{
cout << "exception while accessing vector's data" << endl;
}