On Monday, 25 July 2022 at 09:04:29 UTC, pascal111 wrote:
I have small C program that uses a pointer to change the start
address of a string, and when I tried to do the same code but
with D, the D code printed the address of the string after I
increased it one step instead of printing the string the
pointer pointing to. Is there a difference between "char *"
pointers between C and D.
No, no difference. Pointers are the same in both languages.
What's different is the behavior of `%s` in `writeln` vs
`printf`. See the documentation on format strings at:
https://dlang.org/phobos/std_format.html
Essentially, `%s` tells the formatter to output something
appropriate for the given type. For an actual D string, you see
the text. For an integral or floating point type, you see the
number. For a pointer, you see the the address. And so on.
Do in your case, to get `writefln` to print the text instead of
the pointer address, you could import `std.string` and use
`fromStringz`:`fromStringz(p)`.
This will give you a D string without allocating any memory.
Basically an immutable slice of the memory pointed at by `p`.
That's fine for this use case, but if you wanted to hang on to
the string beyond the lifetime of the pointer, you'd have to use
`std.conv.to` instead (e.g., `to!string(p)`).
