The float() function in Python is used to convert a given value into a floating-point number. If no argument is provided, it returns 0.0.

Syntax

float([x])

• x (optional): The value to be converted to a floating-point number. It can be a string, integer, or any object that implements the __float__() method.

Return Value

• Returns the floating-point representation of the input value.
• Raises a ValueError if the input cannot be converted to a float.

Examples

1. Converting an integer to a float:

   print(float(5))  # Output: 5.0
   

2. Converting a string to a float: The string must represent a valid number.

   print(float("3.14"))  # Output: 3.14
   print(float("5"))     # Output: 5.0
   

3. Using float() without arguments: When called without arguments, float() returns 0.0.

   print(float())  # Output: 0.0
   

4. Converting a scientific notation string: float() can handle strings in scientific notation.

   print(float("1e3"))  # Output: 1000.0
   

5. Using float() with an object: Any object that defines the __float__() method can be passed to float().

   class MyNumber:
       def __float__(self):
           return 7.5
   
   num = MyNumber()
   print(float(num))  # Output: 7.5
   

6. Handling special float values: You can also convert special values like "NaN" (Not a Number) or "inf" (infinity).

   print(float("nan"))  # Output: nan
   print(float("inf"))  # Output: inf
   

Handling Errors

• If the string does not represent a valid number, Python will raise a ValueError:

  print(float("abc"))  # Raises ValueError: could not convert string to float
  

Summary

• The float() function converts a value to a floating-point number.
• It works with integers, strings, and objects that define __float__().
• If no argument is given, it returns 0.0.
• It can handle scientific notation and special float values like "NaN" and "inf".