How to convert float to integer in Python?

In Python there are two main numeric data types: integers and floats. Integers are whole numbers without decimal points, while floats contain decimal values. Python provides several built-in methods to convert float values to integers ?

Using the int() Function

The int() function converts floating-point numbers to integers by truncating the decimal part. It does not round values − it simply removes everything after the decimal point.

Basic Float to Integer Conversion

Here's a simple example of converting a float to an integer ?

num = 39.98

print('Data type of num:', type(num).__name__) 

# float to int conversion
num = int(num)

print('Converted value and its data type:', num, ', type:', type(num).__name__)

Data type of num: float
Converted value and its data type: 39 , type: int

Converting Float Strings

The int() function cannot directly convert a string containing a float. You must first convert the string to float, then to integer ?

# This will raise a ValueError
try:
    num_str = '1.5'
    result = int(num_str)
except ValueError as e:
    print(f"Error: {e}")

# Correct approach - convert string to float first
num_str = '1.5'
result = int(float(num_str))
print(f"Converted value: {result}")

Error: invalid literal for int() with base 10: '1.5'
Converted value: 1

Floating-Point Precision Edge Case

Due to floating-point precision limitations, some values may appear to round unexpectedly ?

num = 1.9999999999999999

print('Original value:', num)
print('Data type:', type(num).__name__) 

# float to int conversion
converted = int(num)

print('Converted value:', converted, ', type:', type(converted).__name__)

Original value: 2.0
Data type: float
Converted value: 2 , type: int

Using Math Module Functions

The math module provides additional functions for converting floats to integers with different behaviors.

Using math.trunc()

The trunc() function truncates toward zero, similar to int() ?

import math

positive_num = 7.89
negative_num = -7.89

print('Positive:', math.trunc(positive_num))
print('Negative:', math.trunc(negative_num))

Positive: 7
Negative: -7

Using math.floor() and math.ceil()

These functions provide floor (round down) and ceiling (round up) conversions ?

import math

num = 7.3

print('Original:', num)
print('Floor (round down):', math.floor(num))
print('Ceiling (round up):', math.ceil(num))
print('Truncate:', math.trunc(num))

Original: 7.3
Floor (round down): 7
Ceiling (round up): 8
Truncate: 7

Comparison of Methods

Conclusion

Use int() for basic float-to-integer conversion with truncation. Use math.floor() or math.ceil() when you need specific rounding behavior. Remember to convert float strings to float first before applying int().