Append character in alternative format

Question

I have two strings which I need to merge. But I have to merge like below format.

var a = "abc"
var b = "def"

I need to do like : adbecf.

Just an normal a+b with some condition I tried. But not able to solve. Any idea ?

update :

let stringA = "abc"
 let stringB = "def"


func mergeStrings(a: String, b: String) -> String {

    let val = zip(a,b).reduce("") { (result, arg1) in
    let (char1, char2) = arg1
    return result + "\(char1)\(char2)"
}
return val
}

"Just an normal a+b with some condition I tried" What conditions? What have you tried? What's the logic? — Larme, May 09 '19 at 08:56
Related: [How can I interleave two arrays?](https://stackoverflow.com/questions/34951824/how-can-i-interleave-two-arrays) — Martin R, May 09 '19 at 09:00

RajeshKumar R · Accepted Answer · 2019-05-09T14:19:45.400

2

let a = "abc"
let b = "def"
let c = zip(a,b).reduce("") { (result, arg1) in
    let (char1, char2) = arg1
    return result + "\(char1)\(char2)"
}
print(c)//adbecf

in short

let c = zip(a,b).reduce("") { $0 + "\($1.0)\($1.1)" }
print(c)

Using zip(::) with two unequal length strings will end with ignoring remaining strings.

let a = "12345"
let b = "67"
let c = zip(a,b).reduce("") { $0 + "\($1.0)\($1.1)" }
print(c)//"1627"--> 345 is ignored

To fix this use

if a.count > b.count {
    c = c + String(a[b.endIndex...])
} else if b.count > a.count {
    c = c + String(b[a.endIndex...])
}
print(c)//"1627345"

edited May 09 '19 at 14:19

answered May 09 '19 at 08:58

RajeshKumar R

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but my input was abc, def only – Sai Kumar May 09 '19 at 09:09
@SaiKumar Do you have var a = "abc" var b = "def" or any other? – RajeshKumar R May 09 '19 at 09:10
@SaiKumar where and how are you calling mergeStrings() ? – RajeshKumar R May 09 '19 at 09:14
it will return from that method. I just needs to return correct string – Sai Kumar May 09 '19 at 09:15
@SaiKumar you are passing some other string to this method. Use print(mergeStrings(a:stringA,b:stringB)) – RajeshKumar R May 09 '19 at 09:16

score 1 · Answer 2 · answered May 09 '19 at 09:11

This code handles merging of equally length string and also unequally length strings either inside the loop of a is longer or at the end if b is longer

var out = ""
for (n, c) in a.enumerated() {
    out.append(c)
    if n < b.count {
        out.append(b[b.index(b.startIndex, offsetBy: n)])
    }
}
if b.count > a.count {
    out += b.suffix(a.count)
}

To ignore any trailing characters

var out = ""
for (n, c) in a.enumerated() {
    if n < b.count {
        out.append(c)
        out.append(b[b.index(b.startIndex, offsetBy: n)])
    }
}

Append character in alternative format

2 Answers2