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float() in Python

  • Difficulty Level : Easy
  • Last Updated : 17 Sep, 2021

Python float() function is used to return a floating-point number from a number or a string. 

Syntax:  float(x)

float() Parameters

The method only accepts one parameter and that is also optional to use. Let us look at the various types of argument, the method accepts: 

A number: Can be an integer or a floating-point number.

A String :

  • Must contain numbers of any type.
  • Any left or right whitespaces or a new line is ignored by the method.
  • Mathematical Operators can be used.
  • Can contain NaN, Infinity or inf (any cases)

Values that the float() method can return depending upon the argument passed

  • If an argument is passed, then the equivalent floating-point number is returned.
  • If no argument is passed then the method returns 0.0.
  • If any string is passed that is not a decimal point number or does not match any cases mentioned above then an error will be raised.
  • If a number is passed outside the range of Python float then OverflowError is generated.

float in Python example

Example 1: How float() works in Python

Python3




# Python program to illustrate
# Various examples and working of float()
# for integers
print(float(21.89))
 
# for floating point numbers
print(float(8))
 
# for integer type strings
print(float("23"))
 
# for floating type strings
print(float("-16.54"))
 
# for string floats with whitespaces
print(float("     -24.45   \n"))
 
# for inf/infinity
print(float("InF"))
print(float("InFiNiTy"))
 
# for NaN
print(float("nan"))
print(float("NaN"))
 
# Error is generated at last
print(float("Geeks"))

Output: 

21.89
8.0
23.0
-16.54
-24.45
inf
inf
nan
nan

All lines are executed properly but the last one will return an error: 

Traceback (most recent call last):
  File "/home/21499f1e9ca207f0052f13d64cb6be31.py", line 25, in 
    print(float("Geeks"))
ValueError: could not convert string to float: 'Geeks'

Example 2: float() for infinity and Nan

Python3




# Python program to illustrate
# Various examples and working of float()
 
# for inf/infinity
print(float("InF"))
print(float("InFiNiTy"))
 
# for NaN
print(float("nan"))
print(float("NaN"))

Output:

inf
inf
nan
nan

Example 3: Converting an Integer to a Float in Python

Python3




# python code to convert int
# float
number = 90
result = float(number)
 
print(result)

Output:

90.0

Example 4: Converting a String to a Float in Python

Python3




# python code to convert string
# to float
string = "90"
result = float(string)
 
print(result)

Output:

90.0

Example 5: Python float() exception

Python3




number = "geeks"
try:
    print(float(number))
except ValueError as e:
    print(e)

Output:

could not convert string to float: 'geeks'


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