What is the math.Floor() Function in Golang

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The math.Floor() function in Golang is “used to find the rounded-down or the floor value of a decimal number“.

Syntax

func Floor(x float64) float64

Parameters

x: The function accepts only one argument of type float64.

There are some exceptions I would like to mention here.

  1. Inf: If you pass an infinite value(±Inf), the return value will be the same as the argument.
  2. NAN: If you pass a NAN value, it returns NAN.
  3. 0: If you pass the (±)0 argument, it returns the same value as an argument.

Return value

The Floor() function returns a single value of the argument rounded down to the nearest whole number whose data type is float64.

Example 1: Use of math.Floor() function

To use the math.Floor() function, import a math package.

package main

import (
  "fmt"
  "math"
  "reflect"
)

func main() {
  var floating_point = 19.21
  fmt.Println(floating_point)
  fmt.Print("The data type is: ", reflect.TypeOf(floating_point), "\n")
 
  var rounded_down = math.Floor(floating_point)
  fmt.Println(rounded_down)
  fmt.Print("The data type is: ", reflect.TypeOf(rounded_down), "\n")
}

Output

19.21
The data type is: float64
19
The data type is: float64

We declared a float64 value in this example and printed its data type using the reflect.TypeOf() function.

Using math.Floor() function, we rounded a value from 19.21 to 19. Although an output value seems like an integer, it is float64 as we printed its data type after conversion.

Example 2: Passing Inf, NAN, and 0

Inf means infinite value, and NAN means not a number and 0. Inf can be positive or negative.

package main

import (
 "fmt"
 "math"
)

func main() {
 var infinity = math.Inf(-1)
 var notANumber = math.NaN()
 var zero = 0

 fmt.Println(infinity)
 fmt.Println(notANumber)
 fmt.Println(zero)
}

Output

-Inf
NaN
0

It returns the same output as the argument passed to the Floor() function.

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