unsupported operand type(s)

[tanusreesen]

Hi All,
I am completely new to python programming language.I was trying to write a program on class.But I am getting this error.Can someone please help me to solve the error I am facing.I am using python2.5.
This is exactly what I wrote and still came up with this error

class point:
    def __init__(self,x=0,y=0):
        self.x=x
        self.y=y
    def _str_(self):
        return '('+ str(self.x)+',  ' + str(self.y) + ')'
    def _add_(self,other):
        return point(self.x+ other.x,self.y+other.y)

>>> p1 =point(3,4)
>>> p2 = point(5,3)
>>> print p1._add_(p2)
<__main__.point instance at 0x0117ED28>
>>> p3 = p1+p2

Traceback (most recent call last):
File "<pyshell#301>", line 1, in <module>
p3 = p1+p2
TypeError: unsupported operand type(s) for +: 'instance' and 'instance'

[bartonc]

Hi All,
I am completely new to python programming language.I was trying to write a program on class.But I am getting this error.Can someone please help me to solve the error I am facing.I am using python2.5.
This is exactly what I wrote and still came up with this error

class point:
    def __init__(self,x=0,y=0):
        self.x=x
        self.y=y
    def _str_(self):
        return '('+ str(self.x)+',  ' + str(self.y) + ')'
    def _add_(self,other):
        return point(self.x+ other.x,self.y+other.y)

>>> p1 =point(3,4)
>>> p2 = point(5,3)
>>> print p1._add_(p2)
<__main__.point instance at 0x0117ED28>
>>> p3 = p1+p2

Traceback (most recent call last):
File "<pyshell#301>", line 1, in <module>
p3 = p1+p2
TypeError: unsupported operand type(s) for +: 'instance' and 'instance'

Special functions (like __init__ and __add__) need two underscores pre and post!

[bartonc]

Also __str__!

[bvdet]

Hi All,
I am completely new to python programming language.I was trying to write a program on class.But I am getting this error.Can someone please help me to solve the error I am facing.I am using python2.5.
This is exactly what I wrote and still came up with this error

class point:
    def __init__(self,x=0,y=0):
        self.x=x
        self.y=y
    def _str_(self):
        return '('+ str(self.x)+',  ' + str(self.y) + ')'
    def _add_(self,other):
        return point(self.x+ other.x,self.y+other.y)

>>> p1 =point(3,4)
>>> p2 = point(5,3)
>>> print p1._add_(p2)
<__main__.point instance at 0x0117ED28>
>>> p3 = p1+p2

Traceback (most recent call last):
File "<pyshell#301>", line 1, in <module>
p3 = p1+p2
TypeError: unsupported operand type(s) for +: 'instance' and 'instance'

Neat post tanusreesen! You are close.

class Point(object):
    def __init__(self, x=0.0, y=0.0):
        self.x = x
        self.y = y
    def __str__(self):
        return '(%0.4f, %0.4f)' % (self.x, self.y)
    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)
    def __sub__(self, other):
        return Point(self.x - other.x, self.y - other.y)
    def __mul__(self, factor):
        return Point(self.x * factor, self.y * factor)
 
 
p1 = Point(2.5, 3.5)
print p1
p2 =  p1 + (Point(2.5, 3.5))
print p2
p3 = p2 - p1
print p3
p4 = p2 * 6
print p4

Output

(2.5000, 3.5000)
(5.0000, 7.0000)
(2.5000, 3.5000)
(30.0000, 42.0000)