How To Convert a String to a Float in Python

data-user_answers_id=”5008″>How To Convert a String to a Float in Python

In this article, we’ll explore how to convert strings to numbers using Python’s float() function. Additionally, we’ll learn how to convert numbers back to strings using Python’s str() function.

It’s crucial to convert data types correctly before using them for calculations and combining them to avoid unexpected errors while the program is running.

Using the float() function:

In Python, you can change a string into a floating-point number using the float() function. This built-in function is designed to convert an object into a floating-point number. Essentially, the float() function invokes the specified object’s float() function internally.

Example

Let’s check out a simple example of converting a string to a float in Python:

string_value = '9.56'
float_value = float(string_value)
print(type(float_value))
print('Float Value =', float_value)

Output

<class 'float'>
Float Value = 9.56

In this example, the float() function is used to convert the string “9.56” to a floating-point number. The resulting value is stored in the variable float_number.

Why do we need to convert a string to float?

When users provide float values through the terminal or when reading from a file, these values are initially in the form of string objects. To carry out operations like addition, multiplication, and more, it’s important to convert these strings into float so that we can perform the required mathematical operations accurately.

Example

value_1 = input('Please enter the first floating-point value:\n')
value_1 = float(value_1)
value_2 = input('Please enter the second floating-point value:\n')
value_2 = float(value_2)
print(f'Sum of {value_1} and {value_2} is {value_1 + value_2}')

Output

Please enter the first floating-point value:
23.34
Please enter the second floating-point value:
365.34
Sum of 23.34 and 365.34 is 388.6799

The sum of 23.34 and 365.34 is calculated to be 388.6799.

Using the str() function:

We can also change a float to a string using the str() function. This becomes useful when we need to combine or concatenate float values with other strings.

Example:

value_1 = 1.23
value_2 = 2.34
value_3 = 3.45
print(f'Concatenation of {value_1} and {value_2} is {str(value_1) + str(value_2)}')
print(f'CSV from {value_1}, {value_2}, and {value_3}:\n{str(value_1)},{str(value_2)},{str(value_3)}')
print(f'CSV from {value_1}, {value_2}, and {value_3}:\n{", ".join([str(value_1), str(value_2), str(value_3)])}')

Output

Concatenation of 1.23 and 2.34 is 1.232.34
CSV from 1.23, 2.34, and 3.45:
1.23,2.34,3.45
CSV from 1.23, 2.34, and 3.45:
1.23, 2.34, 3.45

When we concatenate 1.23 and 2.34, the result is the string ‘1.232.34’. Additionally, this code generates two versions of comma-separated values (CSV).

In the above program, if we skip converting floats to strings, the join() function will cause an exception. Additionally, using the + operator for concatenation won’t work correctly, as it would attempt to add the floating-point numbers instead.

Conclusion:

In this tutorial, we’ve covered the conversion between strings and numbers in Python using the float() and str() functions. Ensuring proper data type conversion is crucial for accurate and error-free operations in a program.

We started by exploring the float() function, which is used to convert strings to floating-point numbers. This is particularly important when handling user input or reading data from files where numeric values are initially in string form. We demonstrated its usage through examples, highlighting the significance of this conversion for mathematical operations.