Thread: WORKAROUND for >> to work with __int64??

It seems that the << and >> operators (which I am using with cin and cout) weren't defined to allow __int64 operands, so you can cout << __int64 anything, and you can't cin >> __int64 anything.

I found a Workaround on the net that allows you to use << so I can cout << __int64, but I can't find one for >>, and I have no clue how to make one.

The workaround for << is:

Code:

#define WORKAROUND

#include<iostream>
using namespace std;

#ifdef WORKAROUND
std::ostream& operator<<(std::ostream& os, __int64 i )
{
    char buf[20];
    sprintf(buf,"%I64d", i );
    os << buf;
    return os;
}

#endif

Anyone know how to make a similar one for >> so I could do something like:

__int64 choice;
cout << "What's your choice?" << endl;
cin >> choice;

The first sentence in the post should read:

It seems that the << and >> operators (which I am using with cin and cout) weren't defined to allow __int64 operands, so you can't cout << __int64 anything, and you can't cin >> __int64 anything.

the code should read:

Code:

#define WORKAROUND   //Uncomment this line to workaround

#include<iostream>
using namespace std;

#ifdef WORKAROUND
std::ostream& operator<<(std::ostream& os, __int64 i )
{
    char buf[20];
    sprintf(buf,"%I64d", i );
    os << buf;
    return os;
}

#endif

This would be easy if I knew how to do any of this. Unfortunately, I had a horrible professor (doesn't seem to know c++ himself), and everything is vague and undefined. All I can do are basic math programs, and the simplest of things.

it may not behave exaclty like cin >> (int) or something when an error occurs since I dont know how all errors are handled, but this should serve your purpose just fine.

Code:

std::istream& operator>>(std::istream& is, __int64 &i )
{
   int neg = 0, c;

   is.eatwhite();
   
   if ((c = is.get()) == '-' && isdigit(is.peek()))
      neg = 1;
   else if (!isdigit(c)) {
      is.setf(ios::failbit);
      is.putback(c);
      return is;
   }
   else
      is.putback(c);

   i = 0;
   for (int k = 0; k < 19; k++) {
      if (isdigit((c = is.get()))) {
         if (unsigned __int64(i*10 + c-'0') < 0x7fffffffffffffff) {
            i = i*10 + c-'0';
         }
      }
      else {
         is.putback(c);
         break;
      }
   }

   if (neg) i *= -1;
   return is;
}

and remember, as with all input through the extraction operator, its good to check the state of ios::fail (<istream>.rdstate & ios::fail) to make sure the user has inputted what you expect (ie. not a char when you expected an int)

Or you could be lazy and upgrade your libraries. The newer MSVC dinkumware standard libraries (that VS.NET ships with) support istream/ostream __int64 operations. They're not free though.