C#•9mo ago

Why does this require a cast?

I have this method:

c#
public string JsonSerialize(bool? mini) {
    mini = mini == null ? true : mini;
    JsonSettings.Formatting = mini ? Formatting.None : Formatting.Indented;
    return JsonConvert.SerializeObject(this, JsonSettings);
}

c#
public string JsonSerialize(bool? mini) {
    mini = mini == null ? true : mini;
    JsonSettings.Formatting = mini ? Formatting.None : Formatting.Indented;
    return JsonConvert.SerializeObject(this, JsonSettings);
}

Even though I've null-checked mini, VS is still telling me that I need an explicit cast to bool on mini ? Formatting.None : Formatting.Indented Why?

16 Replies

Angius•9mo ago

Because mini is of type bool? You canot change a variable's type

public string JsonSerialize(bool? mini)
{
    JsonSettings.Formatting = mini is not false ? Formatting.None : Formatting.Indented;
    return JsonConvert.SerializeObject(this, JsonSettings);
}

public string JsonSerialize(bool? mini)
{
    JsonSettings.Formatting = mini is not false ? Formatting.None : Formatting.Indented;
    return JsonConvert.SerializeObject(this, JsonSettings);
}

You could try pattern matching like this

UnemployedNinjaOP•9mo ago

So using ? is kind of like an entirely new type? In a sense?

Angius•9mo ago

Yes bool? and bool are two different types

UnemployedNinjaOP•9mo ago

I see Makes sense

Angius•9mo ago

To be precise, since bool is a value type, bool? gets lowered by the compiler to Nullable<bool>

UnemployedNinjaOP•9mo ago

Ok, that makes sense Ty

MODiX•9mo ago

Angius

REPL Result: Success

foreach (var v in new bool?[] { null, true, false })                  {                                                                         var check = v is not false;                                           Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is not false' is {check}")  ;
}

foreach (var v in new bool?[] { null, true, false })                  {                                                                         var check = v is not false;                                           Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is not false' is {check}")  ;
}

Console Output

For v being null, the statement 'v is not false' is True
For v being True, the statement 'v is not false' is True
For v being False, the statement 'v is not false' is False

For v being null, the statement 'v is not false' is True
For v being True, the statement 'v is not false' is True
For v being False, the statement 'v is not false' is False

Compile: 464.147ms | Execution: 52.290ms | React with ❌ to remove this embed.

DΣX•9mo ago

foreach (var v in new bool?[] { null, true, false })                  {                          var check = v is true;
Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is not false' is {check}")  ;
}

foreach (var v in new bool?[] { null, true, false })                  {                          var check = v is true;
Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is not false' is {check}")  ;
}

Angius•9mo ago

You need !e to evaluate the code

DΣX•9mo ago

i hate this bot. not telling me how to use it

MODiX•9mo ago

Angius

REPL Result: Success

foreach (var v in new bool?[] { null, true, false })                  {                          var check = v is true;
Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is true' is {check}")  ;
}

foreach (var v in new bool?[] { null, true, false })                  {                          var check = v is true;
Console.WriteLine($"For v being {(v is null ? "null" : v.ToString())}, the statement 'v is true' is {check}")  ;
}

Console Output

For v being null, the statement 'v is true' is False
For v being True, the statement 'v is true' is True
For v being False, the statement 'v is true' is False

For v being null, the statement 'v is true' is False
For v being True, the statement 'v is true' is True
For v being False, the statement 'v is true' is False

Compile: 465.248ms | Execution: 52.642ms | React with ❌ to remove this embed.

DΣX•9mo ago

ok just wanted to point out : null != true and null != false and true != false the nullable bools has exactly 3 possible values, and if you compare against one, the others are false. and if you compare against "not one" there are 2 positive results (just negated). whichever one it is

oke•9mo ago

because bool? is not a bool i read somewhere that behind the scenes, the compiler takes bool? and outputs Nullable<bool> as the type, accounting for any other type (so really its Nullable<T>) i may be wrong though, so take it with a grain of salt

Angius•9mo ago

You might have read it here lol

MODiX•9mo ago

Angius

To be precise, since bool is a value type, bool? gets lowered by the compiler to Nullable<bool>

Quoted by

<@85903769203642368> from #Why does this require a cast? (click here)

React with ❌ to remove this embed.

oke•9mo ago

100% skipped all of that with the assumption it wasnt said already lol

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Why does this require a cast?