Trim String before specific character?

Question

I have a string (asderwt.qwertyu.zxcvbbnnhg) and I want to change it to .qwertyu.zxcvbbnnhg.

I have tried to do this using the following code:

Var str = "asderwt.qwertyu.zxcvbbnnhg"
if let dotRange = str.range(of: ".") {
str.removeSubrange(dotRange.lowerBound..<str.startIndex)
print("AAAAAAAAAA: \(str)")

 }

What is your algorithm here for deciding where to trim? What have you attempted so far? Show your code. — Chris Shaw, May 16 '19 at 06:36

RajeshKumar R · Accepted Answer · 2019-05-16T07:02:33.220

2

Get the first index of the dot and get the substring after that index

let str = "asderwt.qwertyu.zxcvbbnnhg"
if let index = str.firstIndex(where: { $0 == "." }) {
    print(str[index...])//.qwertyu.zxcvbbnnhg
}

edited May 16 '19 at 07:02

answered May 16 '19 at 06:42

RajeshKumar R

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Martin R · Answer 2 · 2019-05-16T06:54:34.783

1

You are on the right track, but here

str.removeSubrange(dotRange.lowerBound..<str.startIndex)

the range bounds are in the wrong order. It should be

var str = "asderwt.qwertyu.zxcvbbnnhg"
if let dotRange = str.range(of: ".") {
    str.removeSubrange(str.startIndex..<dotRange.lowerBound) // <-- HERE
    print("Result: \(str)") // Result: .qwertyu.zxcvbbnnhg
}

You can also use a “partial range”

if let dotRange = str.range(of: ".") {
    str.removeSubrange(..<dotRange.lowerBound)
    print("Result: \(str)") // Result: .qwertyu.zxcvbbnnhg
}

Or with firstIndex(of:) instead of range(of:):

if let dotIndex = str.firstIndex(of: ".") {
    str.removeSubrange(..<dotIndex)
    print("Result: \(str)") // Result: .qwertyu.zxcvbbnnhg
}

edited May 16 '19 at 06:54

answered May 16 '19 at 06:49

Martin R

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Can we do this using `stride` ? – Prashant Tukadiya May 16 '19 at 06:55
1

@PrashantTukadiya: What do you mean? I not see yet how stride would be useful for this task. – Martin R May 16 '19 at 06:57
I have seen this answer so https://stackoverflow.com/a/38980231/4601900 I thought that we can also use it here. may be we can't use stride here – Prashant Tukadiya May 16 '19 at 06:59
@PrashantTukadiya: There the *length* of the substrings is given, and the result is an *array* of substrings. Here we want to split on (the first occurrence of) a certain character. – Martin R May 16 '19 at 07:00

Trim String before specific character?

2 Answers2