# What is float function in Python?

The Python float function converts a given value into a float. The float function takes an argument that can be a number or string with the decimal point. For example:

flt_num = float(10)

flt_str = float(“10.5”)

### Syntax of using float function

class float([x])

Where x argument rules are as follows:

• If x is a string then it should be a decimal number.
• For a string, you may optionally use a ‘+’ or ‘–‘ sign. Using the ‘+’ sign does not affect the result.
• If x is a string and contains leading or trailing spaces, these are removed.
• A string representing NaN (not-a-number) may also be used.
• An int or float number can be used as an argument. In that case, the floating point number with the same value is returned.

### An example of converting a string to float

In the example below, we have a decimal number as a string that is used as an argument in the float Python function. The code and result are shown below:

```#Python float demos

flt_x = float("43.59")
print("The returned float number:" ,flt_x)```

The result:

The returned float number: 43.59

### Using leading and trailing spaces in string example

Now,  I used leading and trailing spaces with a decimal number in the string. As mentioned earlier, the spaces should be removed by float function. See the code and output below:

```#Python float demos

str_num = "   55.48   "

flt_spaces = float(str_num)

print("Original string:" ,str_num)
print("After float function:" ,flt_spaces)```

Output:

You see, the original string shows spaces while as I displayed the value after using the float function, the spaces in left and right are removed.

### The example of using int and float

This example shows the returned values after using an int and floating numbers in the float function.

```int_num = 35

flt_num = 61.89

print("Int after float function:" ,float(int_num))

print("Float number after:" ,float(flt_num))```

The output:

Int after float function: 35.0

Float number after: 61.89

### An example of checking if a value is NaN

The example below uses math module and checks if the value is NaN by float function:

```import math

print (math.isnan(float('NaN')))

print (math.isnan(25.0))```

The result:

True

False

### What if an alphabet is used in float function?

A ValueError will be generated if alphabets are given in the float function. Have a look at an example below:

```str_flt = "test"

print (float(str_flt))```

The output:

ValueError: could not convert string to float: ‘test’
##### Author - Atiq Zia

Atiq is the writer at jquery-az.com, an online tutorial website started in 2014. With a passion for coding and solutions, I navigate through various languages and frameworks. Follow along as we solve the mysteries of coding together!