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# Python bin() function

```The Python function bin() returns the binary representation of a given integer.
In case a non-integer class is given, the __index__() method is used.

bin() on integer

```
int1 = 5
print(bin(int1))
```

In this example, the binary representation of the integer is returned. The prefix 0b is included to indicate a binary representation.

0b101

remove prefix

To remove the prefix, we slice off the prefix:

```
int1 = 5
print(bin(int1)[2:])
```

to receive just the binary code:

101

reverse bin() function

To reverse the bin() function we simply use the int() function:

```
int1 = 5
bin1 = bin(int1)
print(int(bin1, 2))
```

to receive the original integer again:

5

bin() on non-integer

```
class Calc:
a=2.5
b=2.5
def __index__(self):
return int(self.a + self.b);

calc1 = Calc()
print(bin(calc1))
```

The binary representation of the sum 5 is returned:

0b101

bin() syntax

The syntax of the bin() function is:

`bin(integer)`

bin() arguments

The bin() function takes exactly one argument of type integer.
If more or less than one argument is given, a TypeError exception is raised.
If a non-integer type is given, a TypeError exception is raised as well.

bin() return values

The bin() function returns the binary representation of a given integer. The return value is prefixed with 0b, and the type of the return value is str.
```