Programming in Python 1
About Lesson

1.4 Casting 

Type casting, or type conversion, is converting the data type of a value to another data type. In Python, you can manually cast data types using built-in functions. This is extremely beneficial when you want to perform operations requiring a specific data type or when working with data from multiple sources that might be different.

Using int()

The int() function casts a value to an integer. This is quite useful when you are reading numeric data from a file or user input in string form and wish to perform integer arithmetic on it. Remember that int() on a float truncates the decimal part; it does not round the number.

x = int(2.8)  # Returns 2
y = int("10")  # Returns 10

Using float()

The float() function casts a value to a floating-point number. This is particularly handy when performing decimal arithmetic operations on numbers. Like int(), float() can convert from both integers and strings.

x = float(2)     # Returns 2.0
y = float("2.8") # Returns 2.8

Using str()

The str() function converts a value to a string. This becomes essential when concatenating numerical values with strings or writing data to a file in string format.

x = str(2)    # Returns '2'
y = str(2.8)  # Returns '2.8'


Points to Note

  • Loss of Information: Be cautious when casting from float to int, as you will lose the decimal information.
  • TypeErrors: Casting might lead to TypeError if the conversion is not feasible. For instance, converting a string with alphabetical characters to an int or float will raise an error.
  • Data Consistency: Always keep track of the original data type and the type you have cast it to, as the transformation might affect the outcomes of your operations.


In essence, typecasting is an indispensable tool in Python programming. It enables smoother data manipulation and ensures that variables are of the correct data type for specific operations. Understanding how to cast between integers, floats, and strings effectively will undeniably enrich the programming toolkit.

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