.NET Float Precision appears to be 9 digits?

Question

I'm porting an app from .NET to the Mono Runtime, and at one point in the code I can see that a float has the value `158136.422`. My understanding of float was that it was 7 digit precision, so how is that number acceptable? Mono trims it to 7 digits as I'd expect. If in C# I do ``` float f = 158136.422f; ``` It gets rounded to 158136.4.

Accepted Answer

When you write this code:

```
float f = 158136.422f;
```

The exact value assigned to `f` is `158136.421875`.

How many digits are output in a string representation is a different matter.

When I use:

```
float f = 158136.422f;
Console.WriteLine(f);
Console.WriteLine(f.ToString("r"));
```

I get results of:

```
158136.4
158136.422
```

on both Mono and .NET.

.NET Float Precision appears to be 9 digits?

Solution

Problem