VARIABLES AND ASSIGNMENTS
VARIABLES AND ASSIGNMENTS
Variables represent labelled storage locations, whose values can be manipulated during program run.
In python ,to create a variable, just assign to its name the value of appropriate type. For example, to create a variable namely Student to hold student’s name and variable age to hold student’s age, you just need to write somewhat similar is shown below:
Student=” Jacob”
Age=16
Python will internally create labels referring to these values as shown below.
Dynamic Typing
In python, as you have learnt, a variable is defined by assigning to it some value (of a particular type such as numeric, string etc.)
X=10
We can say that variable x is referring to a value of integer type.
Later in your program, if you reassign a value of some other type to variable x, python will not complain (no error will be raised),e.g.,
X=10
Print(x)
X=’’Hello World”
Print(x)
Above code will yield the output as:
10
Hello World
So, you can think of python variables as labels associated with objects (literal values in our case here); with dynamic typing, python makes a label refer to new value with new assignment (Fig.1.2) following figure illustrates it.
Dynamic Typing vs. Static Typing
Dynamic typing is different from static typing. In static typing, a data type is attached with a variable when it is defined first and it is fixed. That is, data type of a variable cannot be changed in static typing whereas there is no such restriction in dynamic typing, which is supported by python.
Multiple assignments
Python is very versatile with assignments. Let’s see how.
- Assigning same value to multiple variables. You can same value to multiple variables in a single statement, e.g., a=b=c=10 it will assign value 10 to all three variables a, b, c.
- Assigning multiple values to multiple variables. You can even assign multiple values to multiple variables in single statement, e.g., x, y, z= 10, 20, 30It will assign the values order wise, i.e., first variable is given first value, second variable the second value and so on. That means, above statement will assign value 10 to x, 20 to y and 30 to y and 30 to z .if you want to swap values of x and y you just need write to follow : x, y = y, x in python, assigning a value to a variable means, variable’s label is referring to that value.