Re: Cannot implicitly convert expression () of type char [1024] to IOREQ *
On Tuesday, 29 November 2016 at 23:33:19 UTC, Ali Çehreli wrote: On 11/29/2016 07:30 AM, Anders S wrote: > INTargv[1];/* list of arguments */ In addition to what Nemanja Boric wrote, the recommended array syntax in D is the following: INT[1] argv; > char sbuf[1024]; > io = (IOREQ *)buf; // Not accepted in dlang You must use the cast keyword, the pointer to first element of an array is .ptr, and I think you meant sbuf: io = cast(IOREQ *)sbuf.ptr; > st = write(fd, sbuf, 1024); // You can use the .length property of arrays: st = write(fd, sbuf, sbuf.length); Ali Thanks you all guys, and the cast (IOREQ *) ... did the trick!! I'll have a look at your other comments aswell on struct a.s.o. /anders
Re: Cannot implicitly convert expression () of type char [1024] to IOREQ *
On Tuesday, 29 November 2016 at 23:33:19 UTC, Ali Çehreli wrote: On 11/29/2016 07:30 AM, Anders S wrote: > INTargv[1];/* list of arguments */ Speculation, but given that you say "list of args" is it possible OP means to use int[0] for an inline array. In addition to what Nemanja Boric wrote, the recommended array syntax in D is the following: INT[1] argv; > char sbuf[1024]; > io = (IOREQ *)buf; // Not accepted in dlang You must use the cast keyword, the pointer to first element of an array is .ptr, and I think you meant sbuf: io = cast(IOREQ *)sbuf.ptr; > st = write(fd, sbuf, 1024); // You can use the .length property of arrays: st = write(fd, sbuf, sbuf.length); Ali
Re: Cannot implicitly convert expression () of type char [1024] to IOREQ *
On 11/29/2016 07:30 AM, Anders S wrote: > INTargv[1];/* list of arguments */ In addition to what Nemanja Boric wrote, the recommended array syntax in D is the following: INT[1] argv; > char sbuf[1024]; > io = (IOREQ *)buf; // Not accepted in dlang You must use the cast keyword, the pointer to first element of an array is .ptr, and I think you meant sbuf: io = cast(IOREQ *)sbuf.ptr; > st = write(fd, sbuf, 1024); // You can use the .length property of arrays: st = write(fd, sbuf, sbuf.length); Ali
Re: Use class template as a type
On Tuesday, 29 November 2016 at 15:56:23 UTC, Jerry wrote:
abstract class MyClass {}
abstract class MyClassImpl(T)
Oops, forgot MyClassImpl should extend from MyClass.
abstract class MyClassImpl(T) : MyClass {
...
}
Re: Use class template as a type
On Monday, 28 November 2016 at 11:26:41 UTC, dm wrote:
```
abstract class MyClass(T)
{
public:
@property const(T) value(){return _value;}
@property void value(T val){_value = val;}
...
private:
T _value;
...
}
To avoid having to use the Object class directly you can make an
base class of the class template.
Like:
```
abstract class MyClass {}
abstract class MyClassImpl(T)
{
public:
@property const(T) value(){return _value;}
@property void value(T val){_value = val;}
...
private:
T _value;
...
}
MyClassInt and float inherits from MyClassImpl
```
And use it like:
```
void main() {
MyClass[] objs;
objs ~= new MyClassFloat();
objs ~= new MyClassInt();
}
```
Re: Cannot implicitly convert expression () of type char [1024] to IOREQ *
On Tuesday, 29 November 2016 at 15:30:33 UTC, Anders S wrote:
Hi guys,
I want to write into a fifo pipe using write( ...)
Now a gather my data into my own struct IOREQ so in order to
write I have to cast into an char buffer.
My problem in dlang is that it doesn't accept the casting
(IOREQ *) I get:
Error: Cannot implicitly convert expression () of type
char [1024] to IOREQ*
define FC_GETSTATUS 501;
typedef struct {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request,
including header */
SHORT src;/* source */
INT argv[1];/* list of arguments */
} IOREQ;
int WritePipe(int fd, int mess, int argc)
{
struct IOREQ * io; // my array of data
char sbuf[1024];
io = (IOREQ *)buf; // Not accepted in dlang
io.fc = FC_GETSTATUS;
io.src = getpid();// works
. // add more data
st = write(fd, sbuf, 1024); //
return st;
}
First, instead of:
typedef struct {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src;/* source */
INT argv[1];/* list of arguments */
} IOREQ;
just
struct IOREQ {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src;/* source */
INT argv[1];/* list of arguments */
} IOREQ;
Then, `write` has the following definition:
https://github.com/dlang/druntime/blob/master/src/core/sys/posix/unistd.d#L100
`ssize_t write(int, in void*, size_t);`
so, it accepts pointer to anything, no need to mess with `char[]`:
IOREQ mystruct;
mystruct.src = getpid();
// etc...
// write it out
write(fd, , mystruct.sizeof); // todo: Don't forget
to check for
// the return value,
etc.
Re: Cannot implicitly convert expression () of type char [1024] to IOREQ *
On Tuesday, 29 November 2016 at 15:55:57 UTC, Nemanja Boric wrote:
just
struct IOREQ {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src;/* source */
INT argv[1];/* list of arguments */
} IOREQ;
Sorry, there's an extra IOREQ before and semicolon.
struct IOREQ {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src;/* source */
INT argv[1];/* list of arguments */
}
Cannot implicitly convert expression () of type char [1024] to IOREQ *
Hi guys,
I want to write into a fifo pipe using write( ...)
Now a gather my data into my own struct IOREQ so in order to
write I have to cast into an char buffer.
My problem in dlang is that it doesn't accept the casting (IOREQ
*) I get:
Error: Cannot implicitly convert expression () of type char
[1024] to IOREQ*
define FC_GETSTATUS 501;
typedef struct {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request,
including header */
SHORT src;/* source */
INT argv[1];/* list of arguments */
} IOREQ;
int WritePipe(int fd, int mess, int argc)
{
struct IOREQ * io; // my array of data
char sbuf[1024];
io = (IOREQ *)buf; // Not accepted in dlang
io.fc = FC_GETSTATUS;
io.src = getpid();// works
. // add more data
st = write(fd, sbuf, 1024); //
return st;
}
Re: How can I concatenate a string, a char array and an int
Thanks guys for a really quick answer !! OK, a little bit awkward to use but getting there posting a new question about char * to struct ;) Thanks /anders
Re: Converting all enum members to a string fails with version 2.0.72.0
On Monday, 21 November 2016 at 18:53:59 UTC, Stefan wrote: On Monday, 21 November 2016 at 17:26:37 UTC, Jonathan M Davis wrote: [...] Thanks Jonathan for the explanation. The cast works fine but feels "unsafe". I will wait for the next version. Stefan Version D 2.072.1 Beta fixed my problem.
Re: How can I concatenate a string, a char array and an int
On Tuesday, 29 November 2016 at 10:21:24 UTC, Anders S wrote:
Hi guys,
just started to get into Dlang, comming from C and C++ I like
to use methods like there if possible.
Now I want to catenate something like this, but don't get it to
work
in standard C i code:
char str[80];
sprintf(str, "This is a number = %f", 3.14356);
Now in Dlang and import core.stdc.string and
code:
char [80] str;
sprintf(str, "This is a number = %d", 314356);
writefln("%s", str);
sprintf(str.ptr, "This is a number = %d".toStringz,314356);
but get error
Error: function core.stdc.stdio.sprintf (char* s, const(char*)
format, ...) is not callable using argument types (char[80],
string, int)
because in D arrays do not decay to pointers. To get a null
terminated string use toStringz
Nor does this work
char [50] temp = "This is a number";
string greeting5= temp~" "~314356;
writefln("%s",greeting5);
add a to!string
314356.to!string
result in error:
Error: incompatible types for ((cast(const(char)[])temp ~ " ")
~ (314356)): 'char[]' and 'int'
Any ideas or hints?
/anders
Re: how to copy const struct with indirections to mutable one (of the same type)
29.11.2016 13:49, Mathias Lang пишет: On Tuesday, 29 November 2016 at 10:46:04 UTC, drug wrote: I had the following code: ``` import std.algorithm: equal; [...] You are not calling the (identity) opAssign here, but postblit. To call identity opAssign, you need an already constructed instance: ``` Data mutable_data; mutable_data = const_data; ``` Thanks for clarification!
Re: how to copy const struct with indirections to mutable one (of the same type)
On Tuesday, 29 November 2016 at 10:46:04 UTC, drug wrote: I had the following code: ``` import std.algorithm: equal; [...] You are not calling the (identity) opAssign here, but postblit. To call identity opAssign, you need an already constructed instance: ``` Data mutable_data; mutable_data = const_data; ```
how to copy const struct with indirections to mutable one (of the same type)
I had the following code:
```
import std.algorithm: equal;
struct Data
{
int[3] arr;
}
int main()
{
auto const_data = const(Data)([1, 2, 3]);
assert(const_data.arr[].equal([1, 2, 3]));
Data mutable_data = const_data;
assert(mutable_data.arr[].equal([1, 2, 3]));
return 0;
}
```
It workred fine. Now I replace static array by std.container.Array:
```
import std.algorithm: copy, equal;
import std.container: Array;
struct Data
{
Array!int arr;
this(R)(R r)
{
r.copy(arr[]);
}
ref Data opAssign(const(Data) other)
{
pragma(msg, __FUNCTION__);
import std.range: lockstep;
this.arr.length = other.arr.length;
foreach(ref s, ref d; lockstep(other.arr[], this.arr[]))
d = s;
return this;
}
}
int main()
{
auto const_data = const(Data)([1, 2, 3]);
assert(const_data.arr[].equal([1, 2, 3]));
Data mutable_data = const_data;
assert(mutable_data.arr[].equal([1, 2, 3]));
return 0;
}
```
and it fails now because:
``
Error: conversion error from const(Data) to Data
```
I can solve my problem in other ways but I'd like to know why opAssign
overload doesn't work in this case?
Thank in advance
Re: How can I concatenate a string, a char array and an int
On Tuesday, 29 November 2016 at 10:21:24 UTC, Anders S wrote:
Hi guys,
just started to get into Dlang, comming from C and C++ I like
to use methods like there if possible.
Now I want to catenate something like this, but don't get it to
work
in standard C i code:
char str[80];
sprintf(str, "This is a number = %f", 3.14356);
import std.format;
string str = format("This is a number = %f", 3.14356);
Now in Dlang and import core.stdc.string and
code:
char [80] str;
sprintf(str, "This is a number = %d", 314356);
writefln("%s", str);
but get error
Error: function core.stdc.stdio.sprintf (char* s, const(char*)
format, ...) is not callable using argument types (char[80],
string, int)
Nor does this work
char [50] temp = "This is a number";
string greeting5= temp~" "~314356;
writefln("%s",greeting5);
import std.conv;
string temp = "This is a number";
string greeting5 = temp ~ " " ~ to!string(314356);
result in error:
Error: incompatible types for ((cast(const(char)[])temp ~ " ")
~ (314356)): 'char[]' and 'int'
Any ideas or hints?
/anders
How can I concatenate a string, a char array and an int
Hi guys,
just started to get into Dlang, comming from C and C++ I like to
use methods like there if possible.
Now I want to catenate something like this, but don't get it to
work
in standard C i code:
char str[80];
sprintf(str, "This is a number = %f", 3.14356);
Now in Dlang and import core.stdc.string and
code:
char [80] str;
sprintf(str, "This is a number = %d", 314356);
writefln("%s", str);
but get error
Error: function core.stdc.stdio.sprintf (char* s, const(char*)
format, ...) is not callable using argument types (char[80],
string, int)
Nor does this work
char [50] temp = "This is a number";
string greeting5= temp~" "~314356;
writefln("%s",greeting5);
result in error:
Error: incompatible types for ((cast(const(char)[])temp ~ " ") ~
(314356)): 'char[]' and 'int'
Any ideas or hints?
/anders
Re: Use class template as a type
On 11/29/2016 02:21 AM, Basile B. wrote: The cast from a class type to a sub class in itself does absolutely nothing. That can't be right. A bad downcast gives you null, so it has to check the dynamic type information. Compare with upcasts which are statically known to be correct, so they don't need to check anything at runtime.
