One of my team mate was trying to “templatize” the function she wrote. She Immediately came to me and shown a sample piece of code where she failed to get the input from the console window.

The code was as follows

template
void Foo(int nArraySize)
{
T* pArray = new T[nArraySize];
int nIdx;
cout<<”Enter the items to be”<<endl;
for ( nIdx = 0;nIdx < nArraySize;nIdx++)
{
cin>>pArray[nIdx];
}

cout<<”The array contains”<<endl;
for ( nIdx = 0; nIdx < nArraySize;nIdx++)
{
cout<<pArray[nIdx]<<endl;
}
}
int main()
{
int x;
cin >> x;
switch( x )
{
case 1:
Foo( 3 );
break;
case 2:
Foo ( 3 );
break;
default:
break;
}
}
I’m calling the functions from Switch case, not that the type of the argument is not passing. When I compiled the source using Visual C++ 6, I got following error

1
Enter the items
10.233
The array contains
-858993460
0
10

After entering 10.233, error occurred in the stream input. This exits the for loop which reads the elements for the array.

The root cause of this issue is basic_istream::operator << () function replaced with the int version irrelevant to the type of the function we’ve instantiated.

Ok let’s try with more cases to prove the hypothesis add one more switch case

case 3:
Foo ( 3 );
break;.

Now the see the output

1
Enter the items
123.23
The array contains
1
2
3

In the above test, I still tried the float version. Instead compiler still taking inputs as char which is the last instantiation of function inside the switch case.

I believe this as a problem of Microsoft Visual C++ 6 compiler. There’s no meaning in talking about the unsupported compiler and IDE.
Microsoft Corrected this issue in their latest compiler Visual C++ 2008 (not sure about VS 2005 and 2003 )
I also tried the same source code with other compilers like Intel C++ Compiler and Dev C++ compiler. It’s working perfectly fine. The problem is only with the old version of Visual C++ compiler.
Please feel free to share your view points and hypothesises.