Vector Operation

this is a practice for operator overloading

the functionality of the program

• initialize the vector,
• negate the vector,
• add and subtract vectors from each other,
• multipliy a vector with a constant (both from the left and the right),
• divide a vector with a constant,
• print a vector to arbitrary streams,
• read a vector from a stream,
• calculate the dot product of two vectors,
• compare vectors for equality and inequality,
• get the length of the vector,