Tsahi's answer is correct. Let me add few points to support 
his answer.

1. According to "Pure" object oriented principle, no 
method/routine should exist without the object. In C++, main
() method can be independant and does not need any class 
but Java/C# its static method of "some" class.

2. C++ provides "Friends" which is absolute corruption to 
the OO-Principle of encapsulation.

3. According OO-Principle, everything needs to be object. 
C++ provide inbuilt datatype- int,float etc which are not 
object in their nature. C#/Java also provides same kind of 
datatype but its inner presentation is always object. For 
example: in java you have got wrapper classes and in C#, 
all these types are derived from System.ValueType object.

4. According OO-Principle, one object should have only one 
hierarchical parent reference. In C++, Multiple-Inheritance 
contradicts this principle.