Python Program to Check If a String Is a Number (Float)

In this example, you will learn to check if a string is a number (float).

To understand this example, you should have the knowledge of the following Python programming topics:

• Python Data Types

Using float()

def isfloat(num):
    try:
        float(num)
        return True
    except ValueError:
        return False

print(isfloat('s12'))
print(isfloat('1.123'))

Output

False
True

Here, we have used try except in order to handle the ValueError if the string is not a float.

• In the function isfloat(), float() tries to convert num to float. If it is successful, then the function returns True.
• Else, ValueError is raised and returns False.

For example, 's12' is alphanumeric, so it cannot be converted to float and False is returned; whereas, '1.123' is a numeric, so it is successfully converted to float.