How to remove items from a slice while ranging over it?

Here is a more idiomatic Go way to remove elements from slices.

temp := s[:0]
for _, x := range s {
    if isValid(x) {
        temp = append(temp, x)
    }
}
s = temp

Playground link: https://play.golang.org/p/OH5Ymsat7s9

Note: The example and playground links are based upon @tomasz's answer https://stackoverflow.com/a/20551116/12003457

You don't even need to count backwards but you do need to check that you're at the end of the array where the suggested append() will fail. Here's an example of removing duplicate positive integers from a sorted list:

// Remove repeating numbers
numbers := []int{1, 2, 3, 3, 4, 5, 5}
log.Println(numbers)
for i, numbersCount, prevNum := 0, len(numbers), -1; i < numbersCount; numbersCount = len(numbers) {
    if numbers[i] == prevNum {
        if i == numbersCount-1 {
            numbers = numbers[:i]
        } else {
            numbers = append(numbers[:i], numbers[i+1:]...)

        }
        continue
    }
    prevNum = numbers[i]
    i++

}
log.Println(numbers)

Playground: https://play.golang.org/p/v93MgtCQsaN

I just implement a method which removes all nil elements in slice.

And I used it to solve a leetcode problems, it works perfectly.

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
 func removeNil(lists *[]*ListNode) {
    for i := 0; i < len(*lists); i++ {
        if (*lists)[i] == nil {
            *lists = append((*lists)[:i], (*lists)[i+1:]...)
            i--
        }
    }
}

Try Sort and Binary search.

Example:

package main

import (
    "fmt"
    "sort"
)

func main() {
    // Our slice.
    s := []int{3, 7, 2, 9, 4, 5}

    // 1. Iterate over it.
    for i, v := range s {
        func(i, v int) {}(i, v)
    }

    // 2. Sort it. (by whatever condition of yours)
    sort.Slice(s, func(i, j int) bool {
        return s[i] < s[j]
    })

    // 3. Cut it only once.
    i := sort.Search(len(s), func(i int) bool { return s[i] >= 5 })
    s = s[i:]

    // That's it!
    fmt.Println(s) // [5 7 9]
}

https://play.golang.org/p/LnF6o0yMJGT