The sort Package

The sort package orders slices and provides comparison tools for custom sort rules.

sort.Ints sorts an integer slice in ascending order in place. sort.Strings sorts strings lexicographically, and sort.Slice sorts using a comparison callback. The modern slices package offers generic alternatives.

In-place sorting changes the original slice’s elements, which also affects views sharing the same backing array. When callers require original order, copy the slice first.

Follow this diagram before executing the example. Check where a value or decision changes what runs next.

This example is a complete program. Save it as main.go or paste it into the Go Playground.

Go code

package main

import (
	"fmt"
	"sort"
)

func main() {
	scores := []int{9, 2, 7, 1}
	sort.Ints(scores)
	fmt.Println("Ascending:", scores)
	fmt.Println("Found 7:", sort.SearchInts(scores, 7))
}

Output

Ascending: [1 2 7 9]
Found 7: 2

Ints rearranges scores to [1 2 7 9]. SearchInts performs binary search on the sorted slice and returns the position 2 for the value 7.

• SearchInts expects sorted data; use it only with the appropriate order.
• sort.Ints modifies the input slice rather than creating a fresh copy.

Sort a slice of names, then use sort.SearchStrings to find a chosen name.

Tip: Edit the example above, predict the output, and run the modified code to test your reasoning.

You have practiced The sort Package in a small, self-contained program. The important habit is to predict what runs, inspect the actual output and distinguish the language rule from the particular example.

Before continuing, make sure you can explain the program to someone who has not seen it, including the line that changes its result.