C# “M”在十进制值赋值中代表什么？
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What does the "M" stand for in decimal value assignment?
提问by JCisar
MSDN says:
MSDN 说：
"Without the suffix m, the number is treated as a double, thus generating a compiler error."
“没有后缀 m，数字被视为双精度数，从而产生编译器错误。”
What does the "M" in:
“M”是什么意思：
decimal current = 10.99M;
stand for?
代表？
Is it any different than:
有什么不同：
decimal current = (decimal)10.99
采纳答案by Scott Chamberlain
M makes the number a decimal representation in code.
M 使数字在代码中以十进制表示。
To answer the second part of your question, yes they are different.
要回答问题的第二部分，是的，它们是不同的。
decimal current = (decimal)10.99
is the same as
是相同的
double tmp = 10.99;
decimal current = (decimal)tmp;
Now for numbers larger than sigma it should not be a problem but if you meant decimal you should specify decimal.
现在对于大于 sigma 的数字，这应该不是问题，但如果您的意思是十进制，则应指定十进制。
Update:
更新：
Wow, i was wrong. I went to go check the IL to prove my point and the compiler optimized it away.
哇，我错了。我去检查 IL 以证明我的观点，编译器对其进行了优化。
Update 2:
更新2：
I was right after all!, you still need to be careful. Compare the output of these two functions.
毕竟我是对的！，你还是要小心。比较这两个函数的输出。
class Program
{
static void Main(string[] args)
{
Console.WriteLine(Test1());
Console.WriteLine(Test2());
Console.ReadLine();
}
static decimal Test1()
{
return 10.999999999999999999999M;
}
static decimal Test2()
{
return (decimal)10.999999999999999999999;
}
}
The first returns 10.999999999999999999999but the seccond returns 11
第一个返回10.999999999999999999999但第二个返回11
Just as a side note, double will get you 15 decimal digits of precisionbut decimal will get you 96 bits of precision with a scaling factor from 0 to 28. So you can represent any number in the range ((-296to 296) / 10(0 to 28))
作为旁注， double 将为您提供15 位十进制数字的精度，但 decimal 将为您提供96 位精度，缩放因子为 0 到 28。所以你可以表示范围内的任何数字 ((-2 96to 2 96) / 10 (0 to 28))
回答by dknaack
Description
描述
decimal current = 10.99M;
Tells the compiler you want a decimal number.
告诉编译器你想要一个十进制数。
decimal current = (decimal)10.99
Tells the compiler you want to cast your double 10.99to a decimal.
告诉编译器您想将 double10.99转换为小数。
Some say it stands for money. M because you must use decimals in financial applications. You must use decimals because they are more accurate than floating point numbers (double).
有人说它代表金钱。M 因为您必须在金融应用程序中使用小数。您必须使用小数，因为它们比浮点数（双精度）更准确。
The decimal suffix is M/m since D/d was already taken by double. Although it has been suggested that M stands for money, Peter Golde recalls that M was chosen simply as the next best letter in decimal.
The decimal has more significant figures than the double, therefore it can be more precise- it also takes up slightly more memory. Other than certian math or physics-related algorithms, the double or float should do fine.
十进制后缀是 M/m，因为 D/d 已经被 double 占用了。尽管有人建议 M 代表金钱，但 Peter Golde 回忆说，M 只是被选为十进制中的下一个最佳字母。
十进制比双精度有更多的有效数字，因此它可以更精确——它也占用更多的内存。除了特定的数学或物理相关算法之外，double 或 float 应该可以。
For example
例如
- If you do ANYNUMBER / 0.5d you will not get the half of ANYNUMBER.
If you do ANYNUMBER / 0.5m you will get everytime the half of ANYNUMBER.
Use
decimalfor money- Use
doublefor exchange rates
- 如果你做 ANYNUMBER / 0.5d 你不会得到 ANYNUMBER 的一半。
如果你做 ANYNUMBER / 0.5m 你会得到 ANYNUMBER 的一半。
用
decimal钱- 使用
double的汇率
More Information
更多信息
回答by Ed S.
Well... I think "D" would be confused with double, so... they chose "M"? Maybe for "Money"? Seems a bit silly... but I couldn't find anything definitive.
嗯...我认为“D”会与 混淆double，所以...他们选择了“M”？也许是为了“钱”？看起来有点傻……但我找不到任何确定的东西。
