Python Type Conversion and Type Casting

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Video Lecture

As you know, every value in Python has a data type.Data type tells the compiler or the interpreter how you want to use the data.

Data type also describes that which operations that can be done on the data and the structure in which you want the data to be stored.

In program it often need to change the one type of value to another type.

Type Conversion:

The process of converting the value of one data type (integer, string, float, etc.) to another data type is called type conversion.

Python has two types of type conversion.

1. Implicit
2. Explicit

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Implicit Type Conversion

In Implicit type conversion, Python automatically converts one data type to another data type.

Example :

>>> a = 2
>>> b = 2.5
>>> c = a + b 
>>> print("Data type of a :",type(a))
Data type of a : <class 'int'>
>>> print("Data type of b :",type(b))
Data type of b : <class 'float'>
>>> print("Data type of c :",type(c))
Data type of c : <class 'float'>

In the above example,

• We are adding two variables a and b, storing the value in c.

• As we can see, data type of a is integer, data type of b is float.

• In a system operation cannot be performed until all the data types are not same in expression.

• So, in above example when we are adding first, a gets type cast into float and then it add to b.

• Type casting from int to float is happening automatically.

• So that we get finally result in c as float

  .

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Explicit Type Conversion :

In Explicit Type Conversion, programmers convert the data type of an object to required data type.

Explicit conversion also known as type casting.

For type casting, Python defines type conversion functions, to directly convert one data type to another.

Syntax :

(required_data_type)(expression)

1. int(x, base) : Converts x to an integer. base specifies the base if x is a string.

2. float(x) : Converts x to a floating-point number.

>>> s = "10010"
>>> a = int(s,2)
>>> print ("After converting to integer base 2 : ",a)
After converting to integer base 2 :  18

b = int(s,8)
>>> print ("After converting to integer base 8 : ",b)
After converting to integer base 8 :  4104

c = int(s)
>>> print ("After converting to integer base 10 : ",c)
After converting to integer base 2 :  10010

>>> f = float(s)
>>> print ("After converting to float : ",f)
After converting to float :  10010.0

3. ord(x) : Converts a character to integer.

4. chr(x): Converts an integer to a character.

5. hex() : Converts integer to hexadecimal string.

6. oct() : Converts integer to octal string.

>>> s = 'A'
>>>c = ord(s)
>>> print(c)
65  OUTPUT

>>> i = 65
>>> c = chr(i)
>>> print(c)
A  OUTPUT

>>> c= hex(65)
>>> print(c)
0x41  OUTPUT

>>> c= oct(65)
>>> print(c)
0o101  OUTPUT

7. complex(real [,imag]) : Converts real numbers to complex(real,imag) number.

8. str(x): Converts object x to a string representation.

9. eval(str) : Evaluates a string and returns an object.

>>> c = complex(1,2)
>>> print(c)
(1+2j)  OUTPUT

>>> c= str(10)
>>> print(c)
10  OUTPUT

>>> c = eval('10')
>>> print(c)
10  OUTPUT
>>> c = eval('12.5')
>>> print(c)
12.5  OUTPUT

10. tuple() : This function is used to convert to a tuple.

11. set() : This function returns the type after converting to set.

12. list() : This function is used to convert any data type to a list type.

13. dict() : This function is used to convert a tuple of order (key,value) into a dictionary.

>>> s = 'python'
>>> c = tuple(s)
>>> print(c)
('p', 'y', 't', 'h', 'o', 'n')

>>> c = set(s)
>>> print(c)
{'p', 'h', 'n', 't', 'y', 'o'}

>>> c = list(s)
>>> print(c)
['p', 'y', 't', 'h', 'o', 'n']

>>> tup = (('a', 1) ,('b', 2), ('c', 3))
>>> c = dict(tup)
>>> print(c)
{'a': 1, 'b': 2, 'c': 3}  OUTPUT

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