CODEWITHSUNDEEP
regexstringgo
grotos
grotos

Reputation: 513

Golang Regex: FindAllStringSubmatch to []string

I download a multiline file from Amazon S3 in format like:

ColumnAv1 ColumnBv1 ColumnCv1 ...
ColumnAv2 ColumnBv2 ColumnCv2 ...

the file is of type byte. Then I want to parse this with regex:

matches := re.FindAllSubmatch(file,-1)

then I want to feed result row by row to function which takes []string as input (string[0] is ColumnAv1, string[1] is ColumnBv2, ...).

How should I convert result of [][][]byte to []string containing first, second, etc row? I suppose I should do it in a loop, but I cannot get this working:

for i:=0;i<len(len(matches);i++{
    tmp:=myfunction(???)
}

BTW, Why does function FindAllSubmatch return [][][]byte whereas FindAllStringSubmatch return [][]string?

(Sorry I don't have right now access to my real example, so the syntax may not be proper)

Upvotes: 0

Views: 2820

Answers (2)

Sundrique
Sundrique

Reputation: 637

You can simply iterate through the bytes result as you would do for strings result using two nested loop, and just convert slice of bytes to a string in the second loop:

package main

import "fmt"

func main() {
    f := [][][]byte{{{'a', 'b', 'c'}}}
    for _, line := range f {
        for _, match := range line { // match is a type of []byte
            fmt.Println(string(match))
        }
    }
}

Playground

Upvotes: 1

LeGEC
LeGEC

Reputation: 51810

It's all explained extensively in the package's documentation.
Read the parapgraph which explains :

There are 16 methods of Regexp that match a regular expression and identify the matched text. Their names are matched by this regular expression:

Find(All)?(String)?(Submatch)?(Index)?

In your case, you probably want to use FindAllStringSubmatch.

In Go, a string is just a read-only []byte.
You can choose to either keep passing []byte variables around,
or cast the []byte values to string :

var byteSlice = []byte{'F','o','o'}
var str string

str = string(byteSlice)

Upvotes: 3

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