Integer overflow

29 November 2011

It have sense to never user clear unsigned types in loops in your program to avoid overflow situation. But if you need big numbers range from unsigned types, you can use wrappers like SafeInt. Good article how to use it you can find here.

And little example for VisualStudio: ``` #include #include #include

typedef unsigned long DWORD;

using namespace std;

void CheckOverflow(DWORD val)
{
    if (val == numeric_limits<DWORD>::max())
    {
        cout << "overflow\n";
    }
    else
    {
        cout << "ok\n";
    }
}

int main()
{
    DWORD val = -1;

    cout << "-1\n";
    CheckOverflow(val);

    val = -2;
    cout << "-2\n";
    CheckOverflow(val);

    int v = -2;
    msl::utilities::SafeInt<DWORD> a(0); 

    cout << "DWORD size: " << sizeof(DWORD) << "\n";
    cout << "SafeInt<DWORD> size: " << sizeof(msl::utilities::SafeInt<DWORD>) << "\n";

    a = v;//raise exception

    return 0;
}

```

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