How can I use Regex to replace this string

Question

One string I transferred from JSON to string as below:

"FIELDLIST": [      "Insurance Num",      "Insurance PersonName",      "InsurancePayDate",      "InsuranceFee",      "InsuranceInvType"    ]

I am trying to strip the space and I hope the result is:

"FIELDLIST":["Insurance Num","Insurance PersonName","InsurancePayDate","InsuranceFee","InsuranceInvType"]

and I write the code in c# as follows:

string[] rearrange_sign = { ",", "[", "]", "{", "}", ":" };
string rtnStr = _prepareStr;

for (int i = 0; i < rearrange_sign.Length; i++)
{
    while (true)
    {
        rtnStr = rtnStr.Replace(@rearrange_sign[i] + " ", rearrange_sign[i]);
        rtnStr = rtnStr.Replace(" " + @rearrange_sign[i], rearrange_sign[i]);
        if (rtnStr.IndexOf(@rearrange_sign[i] + " ").Equals(-1) && rtnStr.IndexOf(" " + @rearrange_sign[i]).Equals(-1))
        {
            break;
        }
    }
}

but it doesn't work at all, it seems I have to use Regex to replace,how can I use it??

Answer 1

Use Regular expression (\\s(?=")|\\s(?=\\])|\\s(?=\\[))+

Here is code:

string str = "\"FIELDLIST\": [ \"Insurance Num\", \"Insurance PersonName\", \"InsurancePayDate\", \"InsuranceFee\", \"InsuranceInvType\" ] ";
string result = System.Text.RegularExpressions.Regex.Replace(str, "(\\s(?=\")|\\s(?=\\])|\\s(?=\\[))+", string.Empty);

Answer 2

Just match the spaces which exists between two non-word characters and then replace the matched spaces with empty string.

@"(?<=\W)\s+(?=\W)"

DEMO

Code:

string str = @"""FIELDLIST"": [      ""Insurance Num"",      ""Insurance PersonName"",      ""InsurancePayDate"",      ""InsuranceFee"",      ""InsuranceInvType""    ]";
string result = Regex.Replace(str, @"(?<=\W)\s+(?=\W)", "");
Console.WriteLine(result);

Output:

"FIELDLIST":["Insurance Num","Insurance PersonName","InsurancePayDate","InsuranceFee","InsuranceInvType"]

IDEONE