i have the ints 4, 7, 0 and 1 how can i Concatenate them into four thousand seven hundred and one.

On 11/07/2014 12:11 a.m., Sean Campbell wrote:
> i have the ints 4, 7, 0 and 1 how can i Concatenate them into four
> thousand seven hundred and one.

If we talking at compile time definition:

int myint = 4_7_0_1;

Would work.
However I'll assume its at runtime you really want this.

I.e. converting a string to an integer.

int myint = to!int("4" ~ "7" ~ "0" ~ "1");

Now they are not strings, and the positions of 10^ doesn't change then:

int myint = (1000 * 4) + (100 * 7) + 1;

Rikki Cattermole:

> int myint = to!int("4" ~ "7" ~ "0" ~ "1");

And to concatenate them there is "join" (joiner is not yet usable here, because to!() doesn't yet accept a lazy input, unfortunately).


> Now they are not strings, and the positions of 10^ doesn't change then:
>
> int myint = (1000 * 4) + (100 * 7) + 1;

Even if Phobos doesn't yet have a enumerate() function, you can use a iota+zip+reduce to do this.

Bye,
bearophile

On 07/10/2014 02:22 PM, Rikki Cattermole wrote:
> On 11/07/2014 12:11 a.m., Sean Campbell wrote:
>> i have the ints 4, 7, 0 and 1 how can i Concatenate them into four thousand seven hundred and one.
> 
> If we talking at compile time definition:
> 
> int myint = 4_7_0_1;
> 
> Would work.
> However I'll assume its at runtime you really want this.
> 
> I.e. converting a string to an integer.
> 
> int myint = to!int("4" ~ "7" ~ "0" ~ "1");
> 
> Now they are not strings, and the positions of 10^ doesn't change then:
> 
> int myint = (1000 * 4) + (100 * 7) + 1;

D also has the pow operator, so you can write this as:

    int i = 4*10^^3 + 7*10^^2 + 0*10^^1 + 1*10^^0;

perhaps I'd better state what I'm doing.
i have an array of 4 bytes and a want to convert them to a 32 bit
int
and convert the 32 bit int back into a 4 bytes again.

On 11/07/2014 1:18 a.m., Sean Campbell wrote:
> perhaps I'd better state what I'm doing.
> i have an array of 4 bytes and a want to convert them to a 32 bit
> int
> and convert the 32 bit int back into a 4 bytes again.

Small hack I use in Dakka:

union RawConvTypes(T) {
	T value;
	ubyte[T.sizeof] bytes;

	ubyte[T.sizeof] opCast() {
		return bytes;
	}
}

auto iRCT = RawConvTypes!int(5);
assert(iRCT.bytes == [5, 0, 0, 0]);

Can be quite useful for evil conversions.

On Thursday, 10 July 2014 at 13:51:22 UTC, Rikki Cattermole wrote:
> On 11/07/2014 1:18 a.m., Sean Campbell wrote:
>> perhaps I'd better state what I'm doing.
>> i have an array of 4 bytes and a want to convert them to a 32 bit
>> int
>> and convert the 32 bit int back into a 4 bytes again.
>
> Small hack I use in Dakka:
>
> union RawConvTypes(T) {
> 	T value;
> 	ubyte[T.sizeof] bytes;
>
> 	ubyte[T.sizeof] opCast() {
> 		return bytes;
> 	}
> }
>
> auto iRCT = RawConvTypes!int(5);
> assert(iRCT.bytes == [5, 0, 0, 0]);
>
> Can be quite useful for evil conversions.

this may sound stupid (new to system programming) but how do you convert to int form ubyte[]

Hello,

I may have not understood what you actually want to do, but
aren't std.bitmanip.peek or std.bitmanip.read what you are
looking for ?

http://dlang.org/phobos/std_bitmanip.html#.peek

On Thursday, 10 July 2014 at 13:51:22 UTC, Rikki Cattermole wrote:
> On 11/07/2014 1:18 a.m., Sean Campbell wrote:
>> perhaps I'd better state what I'm doing.
>> i have an array of 4 bytes and a want to convert them to a 32 bit
>> int
>> and convert the 32 bit int back into a 4 bytes again.
>
> Small hack I use in Dakka:
>
> union RawConvTypes(T) {
> 	T value;
> 	ubyte[T.sizeof] bytes;
>
> 	ubyte[T.sizeof] opCast() {
> 		return bytes;
> 	}
> }
>
> auto iRCT = RawConvTypes!int(5);
> assert(iRCT.bytes == [5, 0, 0, 0]);
>
> Can be quite useful for evil conversions.

But as I understood the OP, he want's to use the bytes as decimal digits, i.e.

    assert(my_convert([4,7,0,1]) == 4701);

Reinterpret casting will not do this...

On Thursday, 10 July 2014 at 15:14:21 UTC, Sean Campbell wrote:
> On Thursday, 10 July 2014 at 13:51:22 UTC, Rikki Cattermole wrote:
>> On 11/07/2014 1:18 a.m., Sean Campbell wrote:
>>> perhaps I'd better state what I'm doing.
>>> i have an array of 4 bytes and a want to convert them to a 32 bit
>>> int
>>> and convert the 32 bit int back into a 4 bytes again.
>>
>> Small hack I use in Dakka:
>>
>> union RawConvTypes(T) {
>> 	T value;
>> 	ubyte[T.sizeof] bytes;
>>
>> 	ubyte[T.sizeof] opCast() {
>> 		return bytes;
>> 	}
>> }
>>
>> auto iRCT = RawConvTypes!int(5);
>> assert(iRCT.bytes == [5, 0, 0, 0]);
>>
>> Can be quite useful for evil conversions.
>
> this may sound stupid (new to system programming) but how do you convert to int form ubyte[]

int to ubyte[4]:
  auto iRCT = RawConvTypes!int();
  iRCT.value = 5;
  writeln(iRCT.bytes); // [5, 0, 0, 0]

ubyte[4] to int:
  auto iRCT = RawConvTypes!int();
  iRCT.bytes = [0, 1, 0, 0];
  writeln(iRCT.value); // 256