Golang max function

last modified May 8, 2025

This tutorial explains how to use the max built-in function in Go. We'll cover basic usage with practical examples of finding maximum values.

The max function is used to find the largest value among its arguments. It was introduced in Go 1.21 as part of the new built-in functions for comparisons.

In Go, max works with ordered types like integers, floats, and strings. It returns the maximum value from the provided arguments, which must be of the same type.

Basic max with integers

The simplest use of max compares two integer values. This example demonstrates basic integer comparison.
Note: All arguments must be of the same comparable type.

basic_max.go

package main

import "fmt"

func main() {
    a := 42
    b := 27
    
    maximum := max(a, b)
    fmt.Printf("The max of %d and %d is %d\n", a, b, maximum)
    
    // Can compare more than two values
    c := 99
    fmt.Printf("The max of %d, %d, and %d is %d\n", 
        a, b, c, max(a, b, c))
}

The function returns the largest integer from the provided arguments. It works with two or more values of the same integer type.

Using max with floating-point numbers

The max function works equally well with floating-point numbers. This example shows floating-point comparisons with max.

float_max.go

package main

import "fmt"

func main() {
    x := 3.14
    y := 2.71
    z := 1.618
    
    fmt.Printf("Max of %.2f and %.2f is %.2f\n", x, y, max(x, y))
    fmt.Printf("Max of %.2f, %.2f, and %.2f is %.2f\n", 
        x, y, z, max(x, y, z))
    
    // Works with negative numbers
    fmt.Println("Max of -10.5 and -20.3:", max(-10.5, -20.3))
}

The function correctly handles floating-point comparisons, including negative numbers. It maintains full floating-point precision in the result.

Finding max string value

The max function can compare strings lexicographically. This example shows string comparisons using max.

string_max.go

package main

import "fmt"

func main() {
    s1 := "apple"
    s2 := "banana"
    s3 := "cherry"
    
    fmt.Println("Max string:", max(s1, s2))
    fmt.Println("Max of three strings:", max(s1, s2, s3))
    
    // Case-sensitive comparison
    fmt.Println("Max with different cases:", 
        max("Go", "go", "GO"))
}

String comparison is case-sensitive and follows Unicode lexicographical order. The function returns the string that would appear last in a sorted list.

Using max with custom ordered types

The max function works with any type that supports ordering. This example demonstrates using max with custom types.

custom_type_max.go

package main

import "fmt"

type Temperature float64

func main() {
    t1 := Temperature(23.5)
    t2 := Temperature(19.2)
    t3 := Temperature(25.7)
    
    hottest := max(t1, t2, t3)
    fmt.Printf("The highest temperature is %.1f°C\n", hottest)
    
    // Also works with other custom ordered types
    type Day int
    const (
        Monday Day = iota
        Tuesday
        Wednesday
    )
    fmt.Println("Latest weekday:", max(Monday, Tuesday, Wednesday))
}

The function works with any type that implements ordered comparisons. Custom types must be based on built-in ordered types to work with max.

Edge cases with max function

This example explores edge cases and special behaviors of the max function. It demonstrates handling of NaN values and empty arguments.

edge_cases_max.go

package main

import (
    "fmt"
    "math"
)

func main() {
    // With NaN values
    nan := math.NaN()
    val := 42.0
    fmt.Println("Max with NaN:", max(nan, val))
    fmt.Println("Max with NaN first:", max(val, nan))
    
    // Requires at least one argument
    // This would cause compile-time error:
    // fmt.Println(max()) // invalid operation: max() (no arguments)
    
    // Single argument returns itself
    fmt.Println("Max of single value:", max(7))
}

When NaN values are present, max always returns NaN. The function requires at least one argument and returns it unchanged when only one is provided.

Source

Go language specification

This tutorial covered the max function in Go with practical examples of finding maximum values across different data types.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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