regex to replace characters in a string

Question

I have a string like this val str = "luckycore.util.BigNum("0")", the first five character of the string e.g lucky are dynamic and can change while rest of the string is fixed, what I was trying was to get output as luckyInt(0) i.e replace all charaters except dynamic one with Int and also remove quotes around 0, I tried using replace and substring methods and its working fine for me, but I want to get this output using regex, I tried but nothing is working, someone please help.

one more case is:

 input string = richardcore.util.BigNum("0")

 output string = richardInt(0)

"tried using replace and substring methods and its working fine for me, but I want to get this output using regex" <- Why? If you have a working solution use that. There is nothing magic about regular expressions and they are imho overused. — user6073886
– user6073886, Commented Jun 13, 2017 at 15:34

Aamir · Accepted Answer · 2017-06-14 03:30:18Z

1

There is no need for Regex, you can simply do it:

val str = """luckycore.util.BigNum("0")"""
val l = str.replace(str.substring(str.indexOf("core"),str.indexOf("(")).trim,"Int").replace("\"","")

answered Jun 14, 2017 at 3:30

Aamir

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1 Comment

The Archetypal Paul Over a year ago

as long as the dynamic part can never contain "core". Maybe lastIndexOf?

Abhinav Galodha · Accepted Answer · 2017-06-13 15:42:49Z

1

You can try using the Regex ([a-z]{5})(core\.util\.BigNum\(\"0\"\)) and then replace the String with the first captured Group.

You can play with this regex at https://regex101.com/r/1DhgLo/1

I am not familiar with Scala or Java. But the Regex should be pretty much remain the same.

answered Jun 13, 2017 at 15:42

Abhinav Galodha

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6 Comments

Sayim Khan Over a year ago

not wokring, I wanted a working solution, u just answered by asking the same question

Abhinav Galodha Over a year ago

Do you think Regex is not working or the java/scala code is not working ?

Abhinav Galodha Over a year ago

@SayimKhan - Which input values is it failing ?

Sayim Khan Over a year ago

same as typed in above question

Abhinav Galodha Over a year ago

If you open the link, it will show you both the input you specified in questions to be matching. I am not sure what is not working for you..

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Leo C · Accepted Answer · 2017-06-13 18:22:06Z

0

If I understand your requirement correctly, there is no need for Regex. You can define a simple function (in Scala) as follows:

// Replace substring trailing after the first n characters 
def replaceTail(s: String, n: Int, tail: String) = {
  s.substring(0, n) + tail
}

val str1 = """luckycore.util.BigNum("0")"""
replaceTail(str1, 5, "Int(0)")
res1: String = luckyInt(0)

val str2 = """richardcore.util.BigNum("0")"""
replaceTail(str2, 7, "Int(0)")
res2: String = richardInt(0)

edited Jun 13, 2017 at 18:22

answered Jun 13, 2017 at 18:06

Leo C

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1 Comment

The Archetypal Paul Over a year ago

If the OP always knows what the dynamic part is (or just its length), it is of course trivial. So it's a safe assumption the dynamic part is not known, so something slightly more flexible is needed.

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