Python Type Casting - Notesformsc

Table of Contents

Casting means changing a data type to another. It is popular in many programming languages like C/C++, Java, etc. Python also supports the type casting and it is done using casting functions. In python, there are two primary casting operations you can do and they are:

Examples of Type Casting in Python

The example contains following types.

Integer to string
Float to string
Boolean to string

Integer to String

num = 2233
result = str(num)
print(type(result))

The output of the above code is

==== RESTART: C:/Python_projects/type casting/integer_to_string.py =======
<class 'str'>
>>>

Float to String

num_float = 344.55
result = str(num_float)
print(type(result))

Once again the output is a string. Note that we are only checking the type and not printing the actual value.

===== RESTART: C:/Python_projects/type casting/float_to_string.py ========
<class 'str'>
>>>

Boolean to String

bool = True
result = str(bool)
print(type(result))

Here is the output of the above code. Once again it is string, the value True will be "True". Note the double quotes around.

===== RESTART: C:/Python_projects/type casting/Bool_to_String.py =========
<class 'str'>
>>>

Examples of String Type to Other Types

In this section, we will convert other types to its string equivalent.

String to integer
String to float
String to Boolean

String to Integer

str = "Hello World"
str2 = "45"
result = int(str)
print(type(result))

The output of the above program is given below. The str cannot be converted into an integer and produce following error.

==== RESTART: C:/Python_projects/type casting/String to Integer.py =======
Traceback (most recent call last):
  File "C:/Python_projects/type casting/String to Integer.py", line 3, in <module>
    result = int(str)
ValueError: invalid literal for int() with base 10: 'Hello World'
>>>

However, the string “45” is converted to number 45 successfully. See the output below.

String to Float

Now we will check two cases , first we will

convert a number string to float
convert a float number string to float

number_string = "399"
result = float(number_string)
print(type(result))

This was successful and the output is below.

======= RESTART: C:/Python_projects/Number_String_To_Float.py ===========
<class 'float'>
>>>

Now we will convert a float string to float value.

float_string = "3.14"
result = float(float_string)
print(result)
print(type(result))

The output is given below.

======= RESTART: C:/Python_projects/Float_String_to_Float.py =========
3.14
<class 'float'>
>>>

String to Boolean Value

To convert a boolean string such as “True” or “False”, you have to use the ast or Abstract Syntax Trees.

Visit following link to learn more about – ast

It has many utilities function and one of them is ast.literal_aval() that evaluates string to other types such as Boolean.

import ast
boolString = "True"
result = ast.literal_eval(boolString)
print(result)
print(type(result))

The output is given below. Note that the result and its type both are printed.

======= RESTART: C:/Python_projects/bool_string_to_boolean.py ========
True
<class 'bool'>
>>>