binary...prob.

hi ,
we convert from int to hex by
cout << hex << int_value;

to octal
cout << oct << int_value;
to binary
cout << binary << int_value;
but i get the following error
cc0ibaaa.o(.text+0x23):conver~1.cpp: undefined reference to `binary(int)'

what is wrong?

can u post the entire code or at least a little bit more?

well,
actually that is all the code. :)

Code:

---

#include <iostream>
int main(void)
{
int int_value;

cout << binary << int_value;
}

---

and the error is
cc0ibaaa.o(.text+0x23):conver~1.cpp: undefined reference to `binary(int)'

i use dev compiler.

wtf :eek:

first of all you must return a value when using int main
put return 0;
like this

Code:

---


#include <iostream>
int main(void)
{
int int_value;

cout << binary << int_value;
return 0;
}

---

and second what are you hoping the compiler will not just
put the binary of your int_value if you havent told the program how to change the value to binary
is this what you are trying to do?

hex and oct are ANSI standard ios class manipulators, binary is not. Unless your compiler has a special, what you are trying will not work.

You can, of course, write your own manipulators.

>>first of all you must return a value when using int main
>>put return 0;
It's been discussed many times before.... return 0; is not required under C++. As for the matter of style... well that's your choice. Do a search if you want to know more.

One way to do it is with a bitset object:

Code:

---

#include <bitset>
#include <iostream>
#include <limits>
using namespace std;

int main
{
    cout << "267 as unsigned long in binary form: "
        << bitset<numeric_limits<unsigned long>::digits>(267)
        << endl;

    return 0;
}

---

Barring any mistakes, this should output something like:
267 as unsigned long in binary form: 00000000000000000000000100001011

Here are some functions that handle any numeric base up to base-36:

For input:
strtoul() ANSI (string to long)
strtod() ANSI (string to double)

For output:
ultoa() NON-ANSI Microsoft (unsigned long to string)

Someday I'm gonna play around with these and make some example programs. For now, you're on your own (plus a little help from all the other smart people here!)

Here's a little bit of an expansion to hk_mp5's code. Really all it does is make the "cout <<" statement shorter.

Code:

---

class bin {
  int value;

public:
  explicit bin(int baseten) : value(baseten) { } 
  ostream& operator()(ostream &out) const;
};

ostream& bin::operator()(ostream &out) const {
  return out << bitset<8>(value);// change 8 to adjust # digits
}

ostream& operator<<(ostream &out, bin baseten) { return baseten(out); }

int main() {
  int val;
  cout << "Enter a number: ";
  cin >> val;

  cout << val << " in binary is " << bin(val) << endl;

  return 0;
}

---