More 2D array problems

Getting Help
1

Function’s job is to count the number of 1’s in a 3 x 3 subset of a larger array. I translated my C procedure to Go and it works. Then I thought I would get fancy and try a 2 dimensional slice. It doesn’t work.

// Working function translated from C
func count(i int, j int, lx[] string) int {
a := 0

    mstart := max(i-1, 0)
    nstart := max(j-1, 0)
    mstop  := min(i+2, height)
    nstop  := min(j+2, width)

    for m:=mstart; m<mstop; m++    {
        for n:=nstart; n<nstop; n++    {
            if lx[m][n]=='1' {   a++ }
        }
    }
    
    return a
}

// Fancy function that doesn’t work properly
func count(i int, j int, lx[] string) int {
a := 0

    mstart := max(i-1, 0)
    nstart := max(j-1, 0)
    mstop  := min(i+1, height-1)
    nstop  := min(j+1, width-1)

    block := lx[mstart:mstop][nstart:nstop]
    for m:=range block {
        for n, test:=range block[m]   {
            if test=='1' {   a++ }
        }
    }
    
    return a
}
2

Can you describe how the second function does not work? It looks like it won’t compile.

Can you please post a runnable sample using play,golang.org so other can reproduce the problem.

Thank you

3

Just tried it again and it didn’t compile. The compiler complained about ‘n’ not being used. Replaced it with an _ and now it compiles, but it still doesn’t work.

I wrote this to solve the ‘Game of Life’ community puzzle on codingame.com. You can find the whole program there.

4

This

doesn’t do what you probably imagine it does. It is not a 2D slice operation by any measure.

You can still use slicing to do it, though: Go Playground - The Go Programming Language.

2 Likes
5

I didn’t really expect it to work, but hey, maybe this is why Go was invented. Never know until you try. Thanks for the clarity.

6

Can you please post a complete code sample using play.golang.org. Thank you

7

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