Replace a string with another

Question

I want to replace "a" with "an" in a sentence; e.g. "He has a egg in his bag", so that there'd be "an" before "egg".

I tried this:

let newString = "He has a egg in his bag".replacingOccurrences(of: "a", with: "an")
print(newString)

– but I get "he hans an egg in his bang" instead of getting "he has an egg in his bag".

it will replace a with an everywhere in string. if you want to make change on specific position you can approach it by index. — Naqeeb
– Naqeeb, Commented Aug 22, 2019 at 9:50

vadian · Accepted Answer · 2019-08-22 11:07:49Z

3

I know the rule is much more complex than adding an n before a vowel (even that) but this is a solution with Regular Expression.

It adds an n to a single a before a word starting with a vowel. The $1 represents the captured vowel

let string = "He has a egg in a bag"
let newString = string.replacingOccurrences(of: "\\ba\\s([aeiou])", with: "an $1", options: .regularExpression)

edited Aug 22, 2019 at 11:07

answered Aug 22, 2019 at 10:25

vadian

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3 Comments

Martin R Over a year ago

One could use a “word boundary” \b instead of the first \s so that it works at the beginning of a sentence.

vadian Over a year ago

@MartinR This would cause the sentence to start with a space character so you would have to add other parentheses to capture more characters and change the replace term (like in the answer of Thanh).

Martin R Over a year ago

The word boundary is not captured. I mean something like replacingOccurrences(of: "\\ba\\s([aeiou])", with: "an $1", ...). I cannot test it currently.

Angel F Syrus · Accepted Answer · 2019-09-12 12:12:23Z

3

Add some extra space with the letter "a".

Change your code as,

if self.addedText.count > 0{ 
   let newString = self.addedText.replacingOccurrences(of: " a ", with: " an ")
   print(newString)
}

edited Sep 12, 2019 at 12:12

answered Aug 22, 2019 at 9:43

Angel F Syrus

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1 Comment

Awais Mobeen Over a year ago

this will not replace the "a" with "an" if the sentence will be like "a orange was in his bag" so you have to use regex to solve this kind of problem as an answer is given below. thanks

Thanh Vu · Accepted Answer · 2019-08-22 10:59:01Z

1

I capture a before a word begin with a,e,i,o,u using regex and replace.

if self.addedText.count {
  let newString = string.replacingOccurrences(of: "(\\b)a(\\s)([aeiou])", with: "$1an$2$3", options: .regularExpression)
  print(newString)
}

answered Aug 22, 2019 at 10:59

Thanh Vu

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