Variables in Python
Variables in Python
Variables in Python are containers that store values of different types in it. It is a name given to a reserved memory location. The type of variable in Python is defined by the kind of value that is assigned to it using assignment operators. Value assigned to a variable can be changed throughout its lifetime and it is just a name given to a memory location that holds the value. Variable is just used to easily access the value stored at some memory address.
Rules of giving names to variables:
- Name of the variable can begin with either a letter or an underscore. It cannot have a digit or any other character in the beginning.
- They are case-sensitive which means that python, Python and PYTHON are all different.
- Reserved words which are also called the keywords cannot be used as an identifier.
Variable Declaration in Python
In Python, you don’t have to declare a variable before using it to make its presence known and to tell the interpreter the amount of memory it needs to reserve. It is declared automatically when a value is assigned to it.
Example of Variable Creation:
# integer variable creation var_int=34 # string variable creation var_string="Study Experts" # printing values of the variables created above print(var_int) print(var_string)
Output:
34 Study Experts
Parallel Assignment in Python
In python, one value can be assigned to multiple variables in a single line using assignment operator “=”.
Example of Parallel Assignment:
# example of parallel assignment var_a=var_b=var_c=23 # displaying values of the variables created above print(var_a) print(var_b) print(var_c)
Output:
23 23 23
Assigning different values to multiple variables using a single “=”
Example:
#example of assigning multiple values to multiple variables #using a single assignment var_a, var_b, var_c=1,24,56 #printing values of the variables declared above print(var_a) print(var_b) print(var_c)
Output:
1 24 56
Types of Variables in Python
In Python, there are two types of variables, namely:
-
- Local Variables
- Global Variables
Local Variables in Python
Local variables are created inside a function and remain in existence as long as the function is. Their scope is limited to the function they are created in. They do not exist outside of a function.
Example of Local Variables in Python:
# example to show local variables in Python def display(): # local variable known only inside this function str="Welcome to StudyExperts" print(str) # call to display() display()
Output:
Welcome to StudyExperts
Global Variables in Python
Global variables are created outside functions and remain in existence as long as the program is. They can be used both inside and outside a function.
Example of Global Variables:
# example to show global variables in Python # global variable str="Welcome to StudyExperts" def display(): print(str) # call to display() display()
Output:
Welcome to StudyExperts
Global keyword
If a global and a local variable have the same name, then when used inside the function, then changes made to x inside the function will not be reflected outside it because changes were made to the local version of it. To access a global variable inside the function, global keyword is used.
Example of Global keyword:
# example to show global keyword in Python # global variable var_int=23 print("Value of var_int before the call to function change() is ",var_int) # function definition def change(): # using the global variable var_int inside the function global var_int var_int=var_int+2 print("Value of var_int inside the function change() is ",var_int) # call to change() change() print("Value of var_int outside the function change() is ",var_int)
Output:
Value of var_int before the call to function change() is 23 Value of var_int inside the function change() is 25 Value of var_int outside the function change() is 25
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