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digitalmars.D.learn - Concatenates int

reply "Sean Campbell" <sycam.inc gmail.com> writes:
i have the ints 4, 7, 0 and 1 how can i Concatenate them into 
four thousand seven hundred and one.
Jul 10 2014
parent reply Rikki Cattermole <alphaglosined gmail.com> writes:
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;
Jul 10 2014
next sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
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
Jul 10 2014
prev sibling parent reply simendsjo <simendsjo gmail.com> writes:
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;
Jul 10 2014
parent reply "Sean Campbell" <sycam.inc gmail.com> writes:
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.
Jul 10 2014
parent reply Rikki Cattermole <alphaglosined gmail.com> writes:
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.
Jul 10 2014
next sibling parent reply "Sean Campbell" <sycam.inc gmail.com> writes:
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[]
Jul 10 2014
next sibling parent reply "Olivier Pisano" <olivier.pisano laposte.net> writes:
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 ?
Jul 10 2014
parent reply "Sean Campbell" <sycam.inc gmail.com> writes:
On Thursday, 10 July 2014 at 15:51:11 UTC, Olivier Pisano wrote:

 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 ?




std.bitmanip.peek and std.bitmanip.read will do nicely should of 
looked more closely
if I need to Concatenate ints I'l just use a recursive pow based 
on length

int ConcatInt(int[] anint){
	int total = 0;
	for(int i=0;i<anint.length;i++){
		total += anint[i]*10^^(anint.length-i-1);
	}
	return total;
}
Jul 10 2014
parent "sigod" <sigod.mail gmail.com> writes:
On Thursday, 10 July 2014 at 17:30:17 UTC, Sean Campbell wrote:

 if I need to Concatenate ints I'l just use a recursive pow 
 based on length

 int ConcatInt(int[] anint){
 	int total = 0;
 	for(int i=0;i<anint.length;i++){
 		total += anint[i]*10^^(anint.length-i-1);
 	}
 	return total;
 }


With `foreach_reverse` it looks a little better:

```d
int concat_ints(int[] ints)
{
	int result;

	foreach_reverse (i, int_; ints) {
		result += int_ * 10 ^^ (ints.length - i - 1);
	}

	return result;
}
```
Jul 10 2014
prev sibling parent "Yota" <yotaxp thatGoogleMailThing.com> writes:
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
Jul 10 2014
prev sibling parent "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> writes:
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...
Jul 10 2014