go – Page 145 – Tarik Billa

How do I send a JSON string in a POST request in Go

September 24, 2022 by Tarik

I’m not familiar with napping, but using Golang’s net/http package works fine (playground): func main() { url := “http://restapi3.apiary.io/notes” fmt.Println(“URL:>”, url) var jsonStr = []byte(`{“title”:”Buy cheese and bread for breakfast.”}`) req, err := http.NewRequest(“POST”, url, bytes.NewBuffer(jsonStr)) req.Header.Set(“X-Custom-Header”, “myvalue”) req.Header.Set(“Content-Type”, “application/json”) client := &http.Client{} resp, err := client.Do(req) if err != nil { panic(err) } defer … Read more

Removing packages installed with go get

September 24, 2022 by Tarik

It’s safe to just delete the source directory and compiled package file. Find the source directory under $GOPATH/src and the package file under $GOPATH/pkg/<architecture>, for example: $GOPATH/pkg/windows_amd64.

Correct way to initialize empty slice

September 24, 2022 by Tarik

The two alternative you gave are semantically identical, but using make([]int, 0) will result in an internal call to runtime.makeslice (Go 1.16). You also have the option to leave it with a nil value: var myslice []int As written in the Golang.org blog: a nil slice is functionally equivalent to a zero-length slice, even though … Read more

Getting a slice of keys from a map

September 24, 2022 by Tarik

This is an old question, but here’s my two cents. PeterSO’s answer is slightly more concise, but slightly less efficient. You already know how big it’s going to be so you don’t even need to use append: keys := make([]int, len(mymap)) i := 0 for k := range mymap { keys[i] = k i++ } … Read more

Contains method for a slice

September 23, 2022 by Tarik

Mostafa has already pointed out that such a method is trivial to write, and mkb gave you a hint to use the binary search from the sort package. But if you are going to do a lot of such contains checks, you might also consider using a map instead. It’s trivial to check if a … Read more

Convert string to integer type in Go?

September 22, 2022 by Tarik

For example strconv.Atoi. Code: package main import ( “fmt” “strconv” ) func main() { s := “123” // string to int i, err := strconv.Atoi(s) if err != nil { // … handle error panic(err) } fmt.Println(s, i) }

How to avoid annoying error “declared and not used”

September 22, 2022 by Tarik

That error is here to force you to write better code, and be sure to use everything you declare or import. It makes it easier to read code written by other people (you are always sure that all declared variables will be used), and avoid some possible dead code. But, if you really want to … Read more

Iterating over all the keys of a map

September 21, 2022 by Tarik

https://play.golang.org/p/JGZ7mN0-U- for k, v := range m { fmt.Printf(“key[%s] value[%s]\n”, k, v) } or for k := range m { fmt.Printf(“key[%s] value[%s]\n”, k, m[k]) } Go language specs for for statements specifies that the first value is the key, the second variable is the value, but doesn’t have to be present.

Checking the equality of two slices

September 21, 2022 by Tarik

You should use reflect.DeepEqual() DeepEqual is a recursive relaxation of Go’s == operator. DeepEqual reports whether x and y are “deeply equal,” defined as follows. Two values of identical type are deeply equal if one of the following cases applies. Values of distinct types are never deeply equal. Array values are deeply equal when their … Read more

Difference between := and = operators in Go

September 20, 2022 by Tarik

In Go, := is for declaration + assignment, whereas = is for assignment only. For example, var foo int = 10 is the same as foo := 10.