go - How to declare a 2d array of unknown size

Question

I did this for the implementation.

csvData := make([][]string, 100)
for i := range csvData {
                csvData[i] = make([]string, 100)
            }

But I want to remove 100 since I don't know the actual size of the array. I want to push some string type elements into the 2d array. Basically I am reading a CSV file and want to extract its elements and store them in a 2d array. What would be a simple way to do so?

question from:https://stackoverflow.com/questions/65679966/how-to-declare-a-2d-array-of-unknown-size

Answer 1

Here a working example, it creates a 10 by 10 slice.

package main

import (
    "fmt"
)

func main() {
    myData := "data"

    var nestedSlice [][]string
    nestedSize := 10

    for i:=0;i<nestedSize; i++ {

        jSlice := []string{}

        for j:=0;j<nestedSize; j++ {
            jSlice = append(jSlice, fmt.Sprintf("row:%v-col:%v-%v", i, j, myData))
        }

        nestedSlice = append(nestedSlice, jSlice)

    }

    fmt.Printf("result: %v
", nestedSlice)
}

And here is the output showing the 10x10 slice.

result: [[row:0-col:0-data row:0-col:1-data row:0-col:2-data row:0-col:3-data row:0-col:4-data row:0-col:5-data row:0-col:6-data row:0-col:7-data row:0-col:8-data row:0-col:9-data] [row:1-col:0-data row:1-col:1-data row:1-col:2-data row:1-col:3-data row:1-col:4-data row:1-col:5-data row:1-col:6-data row:1-col:7-data row:1-col:8-data row:1-col:9-data] [row:2-col:0-data row:2-col:1-data row:2-col:2-data row:2-col:3-data row:2-col:4-data row:2-col:5-data row:2-col:6-data row:2-col:7-data row:2-col:8-data row:2-col:9-data] [row:3-col:0-data row:3-col:1-data row:3-col:2-data row:3-col:3-data row:3-col:4-data row:3-col:5-data row:3-col:6-data row:3-col:7-data row:3-col:8-data row:3-col:9-data] [row:4-col:0-data row:4-col:1-data row:4-col:2-data row:4-col:3-data row:4-col:4-data row:4-col:5-data row:4-col:6-data row:4-col:7-data row:4-col:8-data row:4-col:9-data] [row:5-col:0-data row:5-col:1-data row:5-col:2-data row:5-col:3-data row:5-col:4-data row:5-col:5-data row:5-col:6-data row:5-col:7-data row:5-col:8-data row:5-col:9-data] [row:6-col:0-data row:6-col:1-data row:6-col:2-data row:6-col:3-data row:6-col:4-data row:6-col:5-data row:6-col:6-data row:6-col:7-data row:6-col:8-data row:6-col:9-data] [row:7-col:0-data row:7-col:1-data row:7-col:2-data row:7-col:3-data row:7-col:4-data row:7-col:5-data row:7-col:6-data row:7-col:7-data row:7-col:8-data row:7-col:9-data] [row:8-col:0-data row:8-col:1-data row:8-col:2-data row:8-col:3-data row:8-col:4-data row:8-col:5-data row:8-col:6-data row:8-col:7-data row:8-col:8-data row:8-col:9-data] [row:9-col:0-data row:9-col:1-data row:9-col:2-data row:9-col:3-data row:9-col:4-data row:9-col:5-data row:9-col:6-data row:9-col:7-data row:9-col:8-data row:9-col:9-data]]

Depending on your use case there might be ways to optimise the for loop so its not n^2 time complexity but that's a different topic completely.