JCisar - 4 months ago 15

C# Question

MSDN says:

"Without the suffix m, the number is treated as a double, thus generating a compiler error."

What does the "M" in:

`decimal current = 10.99M;`

stand for?

Is it any different than:

`decimal current = (decimal)10.99`

Answer

M makes the number a decimal representation in code.

To answer the second part of your question, yes they are different.

```
decimal current = (decimal)10.99
```

is the same as

```
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.

**Update**:

Wow, i was wrong. I went to go check the IL to prove my point and the compiler optimized it away.

**Update 2**:

I was right after all!, you still need to be careful. Compare the output of these two functions.

```
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 `10.999999999999999999999`

but the seccond returns `11`

Just as a side note, double will get you 15 decimal digits of precision but 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 ((-2^{96} to 2^{96}) / 10^{(0 to 28)})