如何在表达式中使用String.Format说明符？

Question

double paintneeded = area/450;

当我运行上述内容时，我将输出设为0.444444444，但我只想0.44。

我尝试了这个，但它引发了一个错误：

double paintneeded = String.Format("{0:0.00}", (area/450));

Console.WriteLine("Number of Gallons paint needed:\t{0}", paintneeded);

如何在此表达式中使用String.Format？或者我可以在Console.WriteLine中使用它吗？如果是这样，我该如何实现呢？

Answer 1

Console.WriteLine("Number of Gallons paint needed:\t{0:F2}", area/450.0);

Answer 2

首先，转换为字符串：

double area = 150;
string paintneeded = string.Format("{0:0.00}", (area/450d)).ToString();

Console.WriteLine("Number of Gallons paint needed:\t{0}", paintneeded); 

第二种方式，转换为double：

double area = 150;
double paintneeded = area/450d;

Console.WriteLine("Number of Gallons paint needed:\t{0:0.00}", paintneeded);