Splitting string before and after certain parameters in Go

Question

My string splitting skills are really poor using Go. I don't know why but I just can't wrap my head around this one and I've tried different ways to do what I need but I always get the wrong output.

I have this string:

https://docs.google.com/spreadsheets/d/1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM/edit#gid=0

I need to get a key from this URL that is found after '/d/' up until the next '/'.

So the key in this case would be:

1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM

How would I go about doing this?

Ainar-G · Accepted Answer · 2015-08-26 15:04:06Z

5

strings.Index can help you with this:

s := "https://docs.google.com/spreadsheets/d/1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM/edit#gid=0"
i := strings.Index(s, "/d/") + len("/d/")
j := strings.Index(s[i:], "/") + i
fmt.Println(s[i:j]) // Prints "1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM"

Playground: http://play.golang.org/p/Mqnnc_tNFk.

answered Aug 26, 2015 at 15:04

Ainar-G

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1 Comment

Brainstorm Over a year ago

Note that this could panic if the second call to index returns -1 because "/" was not found. Then i > j in s[i:j] which causes panic.

RCZiegler · Accepted Answer · 2015-08-26 15:05:21Z

3

I have never used "go" but it looks like you could utilize

func Split(s, set string) []string

Example:

fmt.Printf("%q\n", strings.Split("https://docs.google.com/spreadsheets/d/1234567890/edit#gid...", "/"))

would return the array

["https:" "" "docs.google.com" "spreadsheets" "d" "1234567890" "edit#gid..."]

answered Aug 26, 2015 at 15:05

RCZiegler

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Comments

VonC · Accepted Answer · 2021-11-09 21:08:18Z

1

Go 1.18 will come with func Cut(s, sep string) (before, after string, found bool), from issue 46336 and CL 351710

s := "https://docs.google.com/spreadsheets/d/1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM/edit#gid=0"
_,after,found := strings.Cut(s, "/d/")
if found {
    // after is 1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM/edit#gid=0"
    before, _, _ := strings.Cut(after, "/")
    // before is 1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM
    fmt.Println(before)
}

No more Index() and SplitN().
A lot of places in stand lib will benefit from strings.Cut(): CL 351711.

answered Nov 9, 2021 at 21:08

VonC

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Comments

Kishore · Accepted Answer · 2015-08-27 02:18:11Z

-1

There are many alternatives to do this, here is the one which I used regular expression.

s := "https://docs.google.com/spreadsheets/d/1k2RNDSh6K7jH3fezjjfgVrHqVstBF569al4F28hqAM/edit#gid=0"
re := regexp.MustCompile("/d/(.*)?/").FindAllStringSubmatch(s, -1)
fmt.Println("found the pattern :", re[0][1])

https://play.golang.org/p/l6B4AE-4to

edited Aug 27, 2015 at 2:18

answered Aug 27, 2015 at 0:27

Kishore

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1 Comment

Dave C Over a year ago

Benchmarks in Go are easy so it's not opinion if it will be "more faster". Using a regexp for such a simple task is ~17× slower and does three vs zero allocations (and that's with precompiling the regexp only once in a global).

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