I am Developing and Operation System in D and when writing writeln("Zaheer"); function, I got an ERROR.
Error: function kernel.dwriteln (char* str) is not callable using argument types (string)
I also tried Casting.
I Developed OS in C and C++ but first time stuck in types.

On Monday, 17 July 2017 at 13:56:24 UTC, Zaheer Ahmed wrote:
> I Developed OS in C and C++ but first time stuck in types.

A lot of C and C++ knowledge will carry over to D, but it isn't exactly the same. D's strings are of type `string` which is another word for `immutable(char)[]`.

immutable means the contents never change. A `[]` slice is a pointer+length pair in a single type.


For your simple case, making it `const char*` should work... but you might want to read up on D's const and array types before going to much further.

On Monday, 17 July 2017 at 14:10:39 UTC, Adam D. Ruppe wrote:
> On Monday, 17 July 2017 at 13:56:24 UTC, Zaheer Ahmed wrote:
>> I Developed OS in C and C++ but first time stuck in types.
>
> A lot of C and C++ knowledge will carry over to D, but it isn't exactly the same. D's strings are of type `string` which is another word for `immutable(char)[]`.
>
> immutable means the contents never change. A `[]` slice is a pointer+length pair in a single type.
>
>
> For your simple case, making it `const char*` should work... but you might want to read up on D's const and array types before going to much further.

Thank you It worked.

On 07/17/2017 05:10 PM, Adam D. Ruppe wrote:
> On Monday, 17 July 2017 at 13:56:24 UTC, Zaheer Ahmed wrote:
>> I Developed OS in C and C++ but first time stuck in types.
> 
> A lot of C and C++ knowledge will carry over to D, but it isn't exactly the same. D's strings are of type `string` which is another word for `immutable(char)[]`.
> 
> immutable means the contents never change. A `[]` slice is a pointer+length pair in a single type.
> 
> 
> For your simple case, making it `const char*` should work...

No, it shouldn't.

Worst, it should work *most* of the time.

If you cast a D string to const char* may or may not null terminate the string.

Shachar

On Tuesday, 18 July 2017 at 03:58:49 UTC, Shachar Shemesh wrote:
> If you cast a D string to const char* may or may not null terminate the string.

I do not recommend explicitly casting. This specific case is a string literal, which is guaranteed to be null terminated and will implicitly cast.

In the cases where it is not null terminated, the compiler will reject it as a type error.