PYTHON INTRODUCTION
Variable and Value
A variable is a memory location where a programmer can store a value. Example : roll_no, amount, name etc.
Value is either string, numeric etc. Example : "Sara", 120, 25.36
Variables are created when first assigned.
Variables must be assigned before being referenced.
The value stored in a variable can be accessed or updated later.
No declaration required
The type (string, int, float etc.) of the variable is determined by Python
The interpreter allocates memory on the basis of the data type of a variable.
Python Variable Name Rules
Must begin with a letter (a - z, A - B) or underscore (_)
Other characters can be letters, numbers or _
Case Sensitive
Can be any (reasonable) length
There are some reserved words which you cannot use as a variable name because Python uses them for other t
,Python Assignment Statements
The assignment statement creates new variables and gives them values. Basic assignment statement in Python i
Syntax
<variable> = <expr>
Where the equal sign (=) is used to assign value (right side) to a variable name (left side). See the following state
>>> Item_name = "Computer" #A String
>>> Item_qty = 10 #An Integer
>>> Item_value = 1000.23 #A floating point
>>> print(Item_name)
Computer
>>> print(Item_qty)
10
>>> print(Item_value)
1000.23
>>>
One thing is important, assignment statement read right to left only.
Example :
a = 12 is correct, but 12 = a does not make sense to Python, which creates a syntax error.
,Multiple Assignment
The basic assignment statement works for a single variable and a single expression. You can also assign a single
more than one variables simultaneously.
Syntax
var1=var2=var3...varn= <expr>
Example :
x=y=z=1
>>> x = y = z = 1
>>> print(x)
1
>>> print(y)
1
>>> print(z)
1
, Here is an another assignment statement where the variables assign many values at the same time.
Syntax
<var>, <var>, ..., <var> = <expr>, <expr>, ..., <expr>
Example :
x, y, z = 1, 2, "abcd“
In the above example x, y and z simultaneously get the new values 1, 2 and "abcd".
>>> x,y,z = 1,2,"abcd"
>>> print(x)
1
>>> print(y)
2
>>> print(z)
abcd
Variable and Value
A variable is a memory location where a programmer can store a value. Example : roll_no, amount, name etc.
Value is either string, numeric etc. Example : "Sara", 120, 25.36
Variables are created when first assigned.
Variables must be assigned before being referenced.
The value stored in a variable can be accessed or updated later.
No declaration required
The type (string, int, float etc.) of the variable is determined by Python
The interpreter allocates memory on the basis of the data type of a variable.
Python Variable Name Rules
Must begin with a letter (a - z, A - B) or underscore (_)
Other characters can be letters, numbers or _
Case Sensitive
Can be any (reasonable) length
There are some reserved words which you cannot use as a variable name because Python uses them for other t
,Python Assignment Statements
The assignment statement creates new variables and gives them values. Basic assignment statement in Python i
Syntax
<variable> = <expr>
Where the equal sign (=) is used to assign value (right side) to a variable name (left side). See the following state
>>> Item_name = "Computer" #A String
>>> Item_qty = 10 #An Integer
>>> Item_value = 1000.23 #A floating point
>>> print(Item_name)
Computer
>>> print(Item_qty)
10
>>> print(Item_value)
1000.23
>>>
One thing is important, assignment statement read right to left only.
Example :
a = 12 is correct, but 12 = a does not make sense to Python, which creates a syntax error.
,Multiple Assignment
The basic assignment statement works for a single variable and a single expression. You can also assign a single
more than one variables simultaneously.
Syntax
var1=var2=var3...varn= <expr>
Example :
x=y=z=1
>>> x = y = z = 1
>>> print(x)
1
>>> print(y)
1
>>> print(z)
1
, Here is an another assignment statement where the variables assign many values at the same time.
Syntax
<var>, <var>, ..., <var> = <expr>, <expr>, ..., <expr>
Example :
x, y, z = 1, 2, "abcd“
In the above example x, y and z simultaneously get the new values 1, 2 and "abcd".
>>> x,y,z = 1,2,"abcd"
>>> print(x)
1
>>> print(y)
2
>>> print(z)
abcd
