如何使正则表达式第一次出现效果。 （科特琳）

Question

Say I have a string that contains a program with notes as follows:

var iString = "int i; //A variable \n" +
"//This is a text with notes \n" +
"//Can you remove them? \n" +
"cout<<i; //printing i \n"

I've created a regular expression that would recognize notes:

var notes1= ("/"+"(\\s)*"+"/"+"(\\w|[^\\w])*"+"\\n").toRegex()

Problem is when writing var newString = iString.replace(notes1,"")

I accept newString to be: "int i; cout<<i \\n"

Instead, the result is: "int i;"

The regular expression 'devours' the whole string till the last "\\n" while I wanted is to end whenever is gets the chance.

How do I define it in Kotlin?

Answer 1

X* is a greedy quantifier (see Quantifiers (The Java™ Tutorials > Essential Classes > Regular Expressions ).

You can use X*? instead which is a reluctant quantifier:

var iString = "int i; //A variable \n" +
        "//This is a text with notes \n" +
        "//Can you remove them? \n" +
        "cout<<i; //printing i \n"
var notes1= ("/"+"(\\s)*"+"/"+"(\\w|[^\\w])*?"+"\\n").toRegex()
println(iString.replace(notes1, ""))

Output:

int i; cout<<i;