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float() in Python

  • Difficulty Level : Easy
  • Last Updated : 17 Nov, 2017

The float() method is used to return a floating point number from a number or a string.
Syntax:

float(x)

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:

  1. A number : Can be an Integer or a floating point number.
  2. 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 to 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.

Now let us look at various examples and the working of float() method.




# 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 which 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'

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