int number = 1000000000;
string whatYouWant = number.ToString("#,##0");
//You get: 1,000,000,000

c# 7.1(也许更早?)通过字符串插值使这变得简单而美观:

var jackpot = 1_000_000; // underscore separators in numeric literals also available since C# 7.0
var niceNumberString = $"Jackpot is {jackpot:n}";
var niceMoneyString = $"Jackpot is {jackpot:C}";

试试这个:

var number = 123456789;
var str = number.ToString("N0");

结果是:“123,456,789”

int num = 98765432;
Console.WriteLine(string.Format("{0:#,#}", num));

就这么简单:

float num = 23658; // for example 
num = num.ToString("N0"); // Returns 23,658

更多信息在这里

您需要相同的格式值和特定于区域性。

 Double value= 1234567;
 value.ToString("#,#.##", CultureInfo.CreateSpecificCulture("hi-IN"));

输出:34567