Python - Type Casting

Sometimes we need to convert a value from one data type to another.

This process is called Type Casting or Type Conversion.

Python provides built-in functions to perform type conversion.

Python supports the following type casting functions:

1. int()
2. float()
3. complex()
4. bool()
5. str()

The int() function converts other data types into an integer.

• Almost every data type can be converted to int, except complex.
• When converting a string, it must contain only a valid integer value.
• The string must represent a base-10 integer.

The float() function converts values into the float data type.

• Almost every data type can be converted to float, except complex.
• When converting a string, it must contain either a valid integer or a valid floating-point value.
• The string must represent a base-10 number.

The complex() function converts values into the complex data type.

Syntax:

complex(x)
or
complex(x, y)
        

Where:

• x represents the real part.
• y represents the imaginary part.

• The complex() function can be used with one or two arguments.
• When using complex(x, y), both x and y must be numeric values or Boolean values.
• String values are not allowed as the second argument.
• If a string is used as the first argument, it must represent a valid integer or floating-point number.

The bool() function converts values into the bool data type.

Rules:

• If the value is 0, the result is False.
• If the value is non-zero, the result is True.

For string values:

• Empty string ("") returns False.
• Any non-empty string returns True.

For example, "False" returns True because it is a non-empty string.

The str() function converts values into the str (string) data type.

• The str() function can convert any Python value into a string.
• The returned value is always of type str.

Function	Purpose
int()	Converts a value to an integer.
float()	Converts a value to a floating-point number.
complex()	Converts a value to a complex number.
bool()	Converts a value to a Boolean value.
str()	Converts a value to a string.

Source Type	int()	float()	complex()	bool()	str()
int	✔	✔	✔	✔	✔
float	✔	✔	✔	✔	✔
complex	✘	✘	✔	✔	✔
bool	✔	✔	✔	✔	✔
str	✔*	✔*	✔*	✔	✔

Note: String conversion to int(), float(), and complex() works only if the string contains a valid numeric value.

• Type casting converts a value from one data type to another.
• Python provides five built-in type casting functions.
• int() and float() cannot convert complex numbers.
• complex() can convert integers, floats, Booleans, and valid numeric strings.
• bool() returns False for zero values and empty strings.
• Any non-zero number or non-empty string returns True.
• str() can convert almost every Python object into a string.

• Python supports automatic as well as explicit type conversion.
• Use int() to convert values into integers.
• Use float() to convert values into floating-point numbers.
• Use complex() to create complex numbers.
• Use bool() to convert values into Boolean values.
• Use str() to convert values into strings.
• Always make sure the value is valid before converting it to another data type.

Function	Converts To
int()	Integer
float()	Floating-point Number
complex()	Complex Number
bool()	Boolean Value
str()	String