# What is the correct way to find the min between two integers in Go?

## Issue

I imported the math library in my program, and I was trying to find the minimum of three numbers in the following way:

`v1[j+1] = math.Min(v1[j]+1, math.Min(v0[j+1]+1, v0[j]+cost))`

where v1 is declared as:

``````t := "stackoverflow"
v1 := make([]int, len(t)+1)
``````

However, when I run my program I get the following error:

``````./levenshtein_distance.go:36: cannot use int(v0[j + 1] + 1) (type int) as type float64 in argument to math.Min
``````

I thought it was weird because I have another program where I write

`fmt.Println(math.Min(2,3))`

and that program outputs `2` without complaining.

so I ended up casting the values as float64, so that `math.Min` could work:

``````v1[j+1] = math.Min(float64(v1[j]+1), math.Min(float64(v0[j+1]+1), float64(v0[j]+cost)))
``````

With this approach, I got the following error:

``````./levenshtein_distance.go:36: cannot use math.Min(int(v1[j] + 1), math.Min(int(v0[j + 1] + 1), int(v0[j] + cost))) (type float64) as type int in assignment
``````

so to get rid of the problem, I just casted the result back to `int`

I thought this was extremely inefficient and hard to read:

``````v1[j+1] = int(math.Min(float64(v1[j]+1), math.Min(float64(v0[j+1]+1), float64(v0[j]+cost))))
``````

I also wrote a small `minInt` function, but I think this should be unnecessary because the other programs that make use of `math.Min` work just fine when taking integers, so I concluded this has to be a problem of my program and not the library per se.

Is there anything that I’m doing terrible wrong?

Here’s a program that you can use to reproduce the issues above, line 36 specifically:
package main

``````import (
"math"
)

func main() {
LevenshteinDistance("stackoverflow", "stackexchange")
}

func LevenshteinDistance(s string, t string) int {
if s == t {
return 0
}
if len(s) == 0 {
return len(t)
}
if len(t) == 0 {
return len(s)
}

v0 := make([]int, len(t)+1)
v1 := make([]int, len(t)+1)

for i := 0; i < len(v0); i++ {
v0[i] = i
}

for i := 0; i < len(s); i++ {
v1[0] = i + 1
for j := 0; j < len(t); j++ {
cost := 0
if s[i] != t[j] {
cost = 1
}
v1[j+1] = int(math.Min(float64(v1[j]+1), math.Min(float64(v0[j+1]+1), float64(v0[j]+cost))))
}

for j := 0; j < len(v0); j++ {
v0[j] = v1[j]
}
}
return v1[len(t)]
}
``````

## Solution

Until Go 1.18 a one-off function was the standard way; for example, the stdlib’s sort.go does it near the top of the file:

``````func min(a, b int) int {
if a < b {
return a
}
return b
}
``````

You might still want or need to use this approach so your code works on Go versions below 1.18!

Starting with Go 1.18, you can write a generic `min` function which is just as efficient at run time as the hand-coded single-type version, but works with any type with `<` and `>` operators:

``````func min[T constraints.Ordered](a, b T) T {
if a < b {
return a
}
return b
}

func main() {
fmt.Println(min(1, 2))
fmt.Println(min(1.5, 2.5))
fmt.Println(min("Hello", "世界"))
}
``````

There’s been discussion of updating the stdlib to add generic versions of existing functions, but if that happens it won’t be until a later version.

`math.Min(2, 3)` happened to work because numeric constants in Go are untyped. Beware of treating float64s as a universal number type in general, though, since integers above `2^53` will get rounded if converted to float64.