如何用逗号替换第一次出现的空格？

Question

I have string as :

string sku= "plmca60     5";

I just wanted to replace first blank space with comma. Hence I tried:

sku.replace(" ",",");

But it given me:

sku="plmca60,,,,,5";

Its because five blank spaces are there in the string. But I want to replace just first occurrence of blank space like;

sku="plmca60,    5"

How can I do like this?

Answer 1

First of all, String.Replace method ¹ returns your string as plmca60,,,,,5 because from documentation;

Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.

You don't need regex for that.

You can use String.IndexOf(string) to get first index of a white space and a little bit Remove and Insert methods combination.

Reports the zero-based index of the first occurrence of the specified string in this instance

string sku = "plmca60     5";
int index = sku.IndexOf(" ");
sku = sku.Remove(index, 1).Insert(index, ",");
Console.WriteLine(sku);

Result will be;

plmca60,    5

Here a demonstration .

1: ^{Remember, it is Replace , not replace . C# is case sensitive language.}

Answer 2

You could use capturing groups like below,

@"^(\S*)\s"

OR

@"^(\S*) "

Replace the matched space by,

$1,

DEMO

\\S matches a non-whitespace character. \\S* matches zero or more non-whitespace characters. ^ asserts that we are at the start.

Code:

string sku= "plmca60 5";
string result = Regex.Replace(sku, @"^(\S*) ", "$1,");
Console.WriteLine(result);
Console.ReadLine();

IDEONE

Answer 3

By using Regex.Replace

var regex = new Regex(Regex.Escape(" "));
var newText = regex.Replace("plmca60     5", ",", 1);

Answer 4

Not an optimized solution but it works,

string sku = "plmca60     5";
string[] skyArr = sku.Split(' ');
skyArr[1] = ",";
string resultString = "";
foreach (string str in skyArr) 
{
     if (str == "")
         resultString += " ";
     else
         resultString += str;
     }
}
Console.WriteLine(resultString);

Answer 5

You can replace all whitespace with ", ". For example:

sku = Regex.Replace(sku, @"\\s+", ", ");

Answer 6

            string sku = "plmca60     5";
            int pos = sku.IndexOf(" ");
            char[] a = sku.ToCharArray();
            a[pos]=a[pos].ToString().Replace(" ", ",").ToCharArray()[0];
            var result = new string(a);

This is dirty way. Meanwhile trying to find out shorter way of doing this.

Answer 7

I would capture 1 space with 0 or more spaces after that in a capture group. That way you can replace it with a comma and the content of the capture-group (which was any spaces after the first one)

Regex.Replace(input, @"\s(\s*)", ",$1");

Online demo

Answer 8

Two line version:

string sku = "plmca60     5";
Console.WriteLine(sku.Insert(sku.IndexOf(" ")).Remove(sku.Index(" "));