总结C#保留小数位数

2.C#保留小数位N位,四舍五入 .

decimal d= decimal.Round(decimal.Parse("0.55555"),2);

3.C#保留小数位N位四舍五入

Math.Round(0.55555,2)

4,C#保留小数位N位四舍五入

double dbdata = 0.55555;
string str1 = dbdata.ToString("f2");//fN 保留N位，四舍五入

5.C#保留小数位N位四舍五入 

string result = String.Format("{0:N2}", 0.55555);//2位

string result = String.Format("{0:N3}", 0.55555);//3位

6. C#保留小数位N位四舍五入

double s=0.55555;
result=s.ToString("#0.00");//点后面几个0就保留几位

C#保留小数位数，及百分号的解决方法:

1、用NumberFormatInfo类来解决:

System.Globalization.NumberFormatInfo provider = new System.Globalization.NumberFormatInfo();
provider.PercentDecimalDigits = 2;//小数点保留几位数.
provider.PercentPositivePattern = 2;//百分号出现在何处.
double result = (double)1 / 3;//一定要用double类型.
Response.Write(result.ToString("P", provider));

2、用toString方法.:

public string getRate(double hcount, double task)
{
string rValue;
string temp = "";
if (task == 0)
{
task = 1;
}
double db = (hcount / task) * 100;
if (hcount >= task)
{
rValue = "100%";
}
else
{
rValue = db.ToString("#0.#0") + "%";
}
return rValue;
}
string str1 = String.Format("{0:N1}",56789); //result: 56,789.0
string str2 = String.Format("{0:N2}",56789); //result: 56,789.00
string str3 = String.Format("{0:N3}",56789); //result: 56,789.000
string str8 = String.Format("{0:F1}",56789); //result: 56789.0
string str9 = String.Format("{0:F2}",56789); //result: 56789.00
string str11 =(56789 / 100.0).ToString("#.##"); //result: 567.89
string str12 =(56789 / 100).ToString("#.##"); //result: 567

补充SQL 四舍五入 保留小数位

保留两位小数

CAST(324.345123 AS DECIMAL(18,2))

CAST(324.346123 AS NUMERIC(18,2))

值为：324.35（默认进行了四舍五入）

四舍五入

round(324.345123,2) 值为：324.350000