Loops/with multiple ranges

From Rosetta Code


Task
Loops/with multiple ranges
You are encouraged to solve this task according to the task description, using any language you may know.

Some languages allow multiple loop ranges, such as the PL/I example (snippet) below.

                                       /* all variables are DECLARED as integers. */
prod= 1; /*start with a product of unity. */
sum= 0; /* " " " sum " zero. */
x= +5;
y= -5;
z= -2;
one= 1;
three= 3;
seven= 7;
/*(below) ** is exponentiation: 4**3=64 */
do j= -three to 3**3 by three ,
-seven to +seven by x ,
555 to 550 - y ,
22 to -28 by -three ,
1927 to 1939 ,
x to y by z ,
11**x to 11**x + one;
/* ABS(n) = absolute value*/
sum= sum + abs(j); /*add absolute value of J.*/
if abs(prod)<2**27 &=0 then prod=prod*j; /*PROD is small enough & J*/
end; /*not 0, then multiply it.*/
/*SUM and PROD are used for verification of J incrementation.*/
display (' sum= ' || sum); /*display strings to term.*/
display ('prod= ' || prod); /* " " " " */


Task

Simulate/translate the above PL/I program snippet as best as possible in your language,   with particular emphasis on the   do   loop construct.

The   do   index must be incremented/decremented in the same order shown.

If feasible, add commas to the two output numbers (being displayed).

Show all output here.

      A simple PL/I   DO  loop  (incrementing or decrementing)  has the construct of:
 
DO variable = start_expression {TO ending_expression] {BY increment_expression} ;
---or---
DO variable = start_expression {BY increment_expression} {TO ending_expression]  ;
 
where it is understood that all expressions will have a value. The variable is normally a
scaler variable, but need not be (but for this task, all variables and expressions are declared
to be scaler integers). If the BY expression is omitted, a BY value of unity is used.
All expressions are evaluated before the DO loop is executed, and those values are used
throughout the DO loop execution (even though, for instance, the value of Z may be
changed within the DO loop. This isn't the case here for this task.
 
A multiple-range DO loop can be constructed by using a comma (,) to separate additional ranges
(the use of multiple TO and/or BY keywords). This is the construct used in this task.
 
There are other forms of DO loops in PL/I involving the WHILE clause, but those won't be
needed here. DO loops without a TO clause might need a WHILE clause or some other
means of exiting the loop (such as LEAVE, RETURN, SIGNAL, GOTO, or STOP), or some other
(possible error) condition that causes transfer of control outside the DO loop.
 
Also, in PL/I, the check if the DO loop index value is outside the range is made at the
"head" (start) of the DO loop, so it's possible that the DO loop isn't executed, but
that isn't the case for any of the ranges used in this task.
 
In the example above, the clause: x to y by z
will cause the variable J to have to following values (in this order): 5 3 1 -1 -3 -5
 
In the example above, the clause: -seven to +seven by x
will cause the variable J to have to following values (in this order): -7 -2 3


Related tasks



ALGOL W[edit]

As with most of the other languages, Algol W doesn't support multiple loop ranges, so a sequence pf loops is used instead.

begin
 % translation of task PL/1 code, with minimal changes, semicolons required by  %
 % PL/1 but redundant in Algol W retained ( technically they introduce empty  %
 % statements after the "if" in the loop body and before the final "end" )  %
 % Note that in Algol W, the loop counter is a local variable to the loop and  %
 % the value of j is not available outside the loops  %
procedure loopBody ( integer value j );  %(below) ** is exponentiation: 4**3=64 %
begin sum := sum + abs(j);  %add absolute value of J.%
if abs(prod)<2**27 and j not = 0 then prod := prod*j; %PROD is small enough & J%
 % ABS(n) = absolute value%
end;  %not 0, then multiply it.%
 %SUM and PROD are used for verification of J incrementation.%
integer prod, sum, x, y, z, one, three, seven;
prod := 1;  %start with a product of unity.  %
sum := 0;  % " " " sum " zero.  %
x := +5;
y := -5;
z := -2;
one := 1;
three := 3;
seven := 7;
for j := -three step three until round( 3**3 ) do loopBody( j );
for j := -seven step x until +seven do loopBody( j );
for j := 555 until 550 - y do loopBody( j );
for j := 22 step -three until -28 do loopBody( j );
for j := 1927 until 1939 do loopBody( j );
for j := x step z until y do loopBody( j );
for j := round( 11**x ) until round( 11**x ) + one do loopBody( j );
write(s_w := 0, " sum= ", sum);  %display strings to term.%
write(s_w := 0, "prod= ", prod);  % " " " "  %
end.
Output:
 sum=         348173
prod=     -793618560

C[edit]

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
 
long prod = 1L, sum = 0L;
 
void process(int j) {
sum += abs(j);
if (labs(prod) < (1 << 27) && j) prod *= j;
}
 
long ipow(int n, uint e) {
long pr = n;
int i;
if (e == 0) return 1L;
for (i = 2; i <= e; ++i) pr *= n;
return pr;
}
 
int main() {
int j;
const int x = 5, y = -5, z = -2;
const int one = 1, three = 3, seven = 7;
long p = ipow(11, x);
for (j = -three; j <= ipow(3, 3); j += three) process(j);
for (j = -seven; j <= seven; j += x) process(j);
for (j = 555; j <= 550 - y; ++j) process(j);
for (j = 22; j >= -28; j -= three) process(j);
for (j = 1927; j <= 1939; ++j) process(j);
for (j = x; j >= y; j -= -z) process(j);
for (j = p; j <= p + one; ++j) process(j);
setlocale(LC_NUMERIC, "");
printf("sum = % 'ld\n", sum);
printf("prod = % 'ld\n", prod);
return 0;
}
Output:
sum  =  348,173
prod = -793,618,560

Factor[edit]

Factor doesn't have any special support for this sort of thing, but we can store iterable range objects in a collection and loop over them.

USING: formatting kernel locals math math.functions math.ranges
sequences sequences.generalizations tools.memory.private ;
 
[let  ! Allow lexical variables.
1 :> prod!  ! Start with a product of unity.
0 :> sum!  ! " " " sum " zero.
5 :> x
-5 :> y
-2 :> z
1 :> one
3 :> three
7 :> seven
 
three neg 3 3 ^ three <range>  ! Create array
seven neg seven x <range>  ! of 7 ranges.
555 550 y - [a,b]
22 -28 three neg <range>
1927 1939 [a,b]
x y z <range>
11 x ^ 11 x ^ 1 + [a,b] 7 narray
 
[
[
 :> j j abs sum + sum!
prod abs 2 27 ^ < j zero? not and
[ prod j * prod! ] when
] each  ! Loop over range.
] each  ! Loop over array of ranges.
 
 ! SUM and PROD are used for verification of J incrementation.
sum prod [ commas ] [email protected] " sum=  %s\nprod= %s\n" printf
]
Output:
 sum=  348,173
prod= -793,618,560

Go[edit]

Nothing fancy from Go here (is there ever?), just a series of individual for loops.

package main
 
import "fmt"
 
func pow(n int, e uint) int {
if e == 0 {
return 1
}
prod := n
for i := uint(2); i <= e; i++ {
prod *= n
}
return prod
}
 
func abs(n int) int {
if n >= 0 {
return n
}
return -n
}
 
func commatize(n int) string {
s := fmt.Sprintf("%d", n)
if n < 0 {
s = s[1:]
}
le := len(s)
for i := le - 3; i >= 1; i -= 3 {
s = s[0:i] + "," + s[i:]
}
if n >= 0 {
return " " + s
}
return "-" + s
}
 
func main() {
prod := 1
sum := 0
const (
x = 5
y = -5
z = -2
one = 1
three = 3
seven = 7
)
p := pow(11, x)
var j int
 
process := func() {
sum += abs(j)
if abs(prod) < (1<<27) && j != 0 {
prod *= j
}
}
 
for j = -three; j <= pow(3, 3); j += three {
process()
}
for j = -seven; j <= seven; j += x {
process()
}
for j = 555; j <= 550-y; j++ {
process()
}
for j = 22; j >= -28; j -= three {
process()
}
for j = 1927; j <= 1939; j++ {
process()
}
for j = x; j >= y; j -= -z {
process()
}
for j = p; j <= p+one; j++ {
process()
}
fmt.Println("sum = ", commatize(sum))
fmt.Println("prod = ", commatize(prod))
}
Output:
sum  =   348,173
prod =  -793,618,560

Kotlin[edit]

Nothing special here, just a series of individual for loops.

// Version 1.2.70
 
import kotlin.math.abs
 
infix fun Int.pow(e: Int): Int {
if (e == 0) return 1
var prod = this
for (i in 2..e) {
prod *= this
}
return prod
}
 
fun main(args: Array<String>) {
var prod = 1
var sum = 0
val x = 5
val y = -5
val z = -2
val one = 1
val three = 3
val seven = 7
val p = 11 pow x
fun process(j: Int) {
sum += abs(j)
if (abs(prod) < (1 shl 27) && j != 0) prod *= j
}
 
for (j in -three..(3 pow 3) step three) process(j)
for (j in -seven..seven step x) process(j)
for (j in 555..550-y) process(j)
for (j in 22 downTo -28 step three) process(j)
for (j in 1927..1939) process(j)
for (j in x downTo y step -z) process(j)
for (j in p..p + one) process(j)
System.out.printf("sum = % ,d\n", sum)
System.out.printf("prod = % ,d\n", prod)
}
Output:
sum  =  348,173
prod = -793,618,560

Perl[edit]

use constant   one =>  1;
use constant three => 3;
use constant seven => 7;
use constant x => 5;
use constant yy => -5; # 'y' conflicts with use as equivalent to 'tr' operator (a carry-over from 'sed')
use constant z => -2;
 
my $prod = 1;
 
sub from_to_by {
my($begin,$end,$skip) = @_;
my $n = 0;
grep{ !($n++ % abs $skip) } $begin <= $end ? $begin..$end : reverse $end..$begin;
}
 
sub commatize {
(my $s = reverse shift) =~ s/(.{3})/$1,/g;
$s =~ s/,(-?)$/$1/;
$s = reverse $s;
}
 
for my $j (
from_to_by(-three,3**3,three),
from_to_by(-seven,seven,x),
555 .. 550 - yy,
from_to_by(22,-28,-three),
1927 .. 1939,
from_to_by(x,yy,z),
11**x .. 11**x+one,
) {
$sum += abs($j);
$prod *= $j if $j and abs($prod) < 2**27;
}
 
printf "%-8s %12s\n", 'Sum:', commatize $sum;
printf "%-8s %12s\n", 'Product:', commatize $prod;
Output:
Sum:          348,173
Product: -793,618,560

Perl 6[edit]

This task is really conflating two separate things, (at least in Perl 6). Sequences and loops are two different concepts and may be considered / implemented separately from each other.

Yes, you can generate a sequence with a loop, and a loop can use a sequence for an iteration value, but the two are somewhat orthogonal and don't necessarily overlap.

Sequences are first class objects in Perl 6. You can (and typically do) generate a sequence using the (appropriately enough) sequence operator and can assign it to a variable and/or pass it as a parameter; the entire sequence, not just it's individual values. It may be used in a looping construct, but it is not necessary to do so.

Various looping constructs often do use sequences as their iterator but not exclusively, possibly not even in the majority.


Displaying the j sequence as well since it isn't very large.

sub comma { ($^i < 0 ?? '-' !! '') ~ $i.abs.flip.comb(3).join(',').flip }
 
my \x = 5;
my \y = -5;
my \z = -2;
my \one = 1;
my \three = 3;
my \seven = 7;
 
my $j = flat
( -three, *+three … 3³ ),
( -seven, *+x^ * > seven ),
( 555 .. 550 - y ),
( 22, *-three …^ * < -28 ),
( 1927 .. 1939 ),
( x, *+z …^ * < y ),
( 11**x .. 11**x + one );
 
put 'j sequence: ', $j;
put ' Sum: ', comma [+] $j».abs;
put ' Product: ', comma ([\*] $j.grep: so +*).first: *.abs > 2²⁷;
 
# Or, an alternate method for generating the 'j' sequence, employing user-defined
# operators to preserve the 'X to Y by Z' layout of the example code.
# Note that these operators will only work for monotonic sequences.
 
sub infix:<to> { $^a ... $^b }
sub infix:<by> { $^a[0, $^b.abs ... *] }
 
$j = cache flat
-three to 3**3 by three ,
-seven to seven by x ,
555 to (550 - y) ,
22 to -28 by -three ,
1927 to 1939 by one ,
x to y by z ,
11**x to (11**x + one) ;
 
put "\nLiteral minded variant:";
put ' Sum: ', comma [+] $j».abs;
put ' Product: ', comma ([\*] $j.grep: so +*).first: *.abs > 2²⁷;
Output:
j sequence: -3 0 3 6 9 12 15 18 21 24 27 -7 -2 3 555 22 19 16 13 10 7 4 1 -2 -5 -8 -11 -14 -17 -20 -23 -26 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 5 3 1 -1 -3 -5 161051 161052
       Sum: 348,173
   Product: -793,618,560

Literal minded variant:
       Sum: 348,173
   Product: -793,618,560

Prolog[edit]

Prolog does not have the richness of some other languages where it comes to loops, variables and the like, but does have some rather interesting features such as difference lists and backtracking for generating solutions.

for(Lo,Hi,Step,Lo)  :- Step>0, Lo=<Hi.
for(Lo,Hi,Step,Val) :- Step>0, plus(Lo,Step,V), V=<Hi, !, for(V,Hi,Step,Val).
for(Hi,Lo,Step,Hi) :- Step<0, Lo=<Hi.
for(Hi,Lo,Step,Val) :- Step<0, plus(Hi,Step,V), Lo=<V, !, for(V,Lo,Step,Val).
 
sym(x,5). % symbolic lookups for values
sym(y,-5).
sym(z,-2).
sym(one,1).
sym(three,3).
sym(seven,7).
 
range(-three,3^3,three). % as close as we can syntactically get
range(-seven,seven,x).
range(555,550-y,1).
range(22,-28, -three).
range(1927,1939,1).
range(x,y,z).
range(11^x,11^x+one,1).
 
translate(V, V) :- number(V), !. % difference list based parser
translate(S, V) :- sym(S,V), !.
translate(-S, V) :- translate(S,V0), !, V is -V0.
translate(A+B, V) :- translate(A,A0), translate(B, B0), !, V is A0+B0.
translate(A-B, V) :- translate(A,A0), translate(B, B0), !, V is A0-B0.
translate(A^B, V) :- translate(A,A0), translate(B, B0), !, V is A0^B0.
 
range_value(Val) :- % enumerate values for all ranges in order
range(From,To,Step),
translate(From,F), translate(To,T), translate(Step,S),
for(F,T,S,Val).
 
calc_values([], S, P, S, P). % calculate all values in generated order
calc_values([J|Js], S, P, Sum, Product) :-
S0 is S + abs(J), ((abs(P)< 2^27, J \= 0) -> P0 is P * J; P0=P),
!, calc_values(Js, S0, P0, Sum, Product).
 
calc_values(Sum, Product) :- % Find the sum and product
findall(V, range_value(V), Values),
calc_values(Values, 0, 1, Sum, Product).
?- calc_values(Sum, Product).
Sum = 348173,
Product = -793618560.

Python[edit]

Pythons range function does not include the second argument hence the definition of _range()

from itertools import chain
 
prod, sum_, x, y, z, one,three,seven = 1, 0, 5, -5, -2, 1, 3, 7
 
def _range(x, y, z=1):
return range(x, y + (1 if z > 0 else -1), z)
 
print(f'list(_range(x, y, z)) = {list(_range(x, y, z))}')
print(f'list(_range(-seven, seven, x)) = {list(_range(-seven, seven, x))}')
 
for j in chain(_range(-three, 3**3, three), _range(-seven, seven, x),
_range(555, 550 - y), _range(22, -28, -three),
_range(1927, 1939), _range(x, y, z),
_range(11**x, 11**x + 1)):
sum_ += abs(j)
if abs(prod) < 2**27 and (j != 0):
prod *= j
print(f' sum= {sum_}\nprod= {prod}')
Output:
list(_range(x, y, z)) = [5, 3, 1, -1, -3, -5]
list(_range(-seven, seven, x)) = [-7, -2, 3]
 sum= 348173
prod= -793618560

REXX[edit]

Programming note:   the (sympathetic) trailing semicolons (;) after each REXX statement are optional,   they are only there to mimic what the PL/I language requires after each statement.

The technique used by this REXX version is to "break up" the various   do   iterating clauses (ranges) into separate   do   loops,   and have them invoke a subroutine to perform the actual computations.

/*REXX program emulates a multiple─range  DO  loop  (all variables can be any numbers). */
prod= 1;
sum= 0;
x= +5;
y= -5;
z= -2;
one= 1;
three= 3;
seven= 7;
 
do j= -three to 3**3 by three  ; call meat; end;
do j= -seven to seven by x  ; call meat; end;
do j= 555 to 550 - y  ; call meat; end;
do j= 22 to -28 by -three ; call meat; end;
do j= 1927 to 1939  ; call meat; end;
do j= x to y by z  ; call meat; end;
do j= 11**x to 11**x + one  ; call meat; end;
 
say ' sum= ' || commas( sum); /*display SUM with commas. */
say 'prod= ' || commas(prod); /* " PROD " " */
exit; /*stick a fork in it, we're done.*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
commas: procedure; parse arg _; n= _'.9'; #= 123456789; b= verify(n, #, "M")
e= verify(n, #'0', , verify(n, #"0.", 'M') ) - 4
do j=e to b by -3; _= insert(',', _, j); end; return _
/*──────────────────────────────────────────────────────────────────────────────────────*/
meat: sum= sum + abs(j);
if abs(prod)<2**27 & j\==0 then prod= prod * j;
return;
output   when using the same variable values:
 sum= 348,173
prod= -793,618,560

zkl[edit]

prod,sum := 1,0;  /* start with a product of unity, sum of 0 */
x,y,z := 5, -5, -2;
one,three,seven := 1,3,7;
foreach j in (Walker.chain([-three..(3).pow(3),three], // do these sequentially
[-seven..seven,x], [555..550 - y], [22..-28,-three], #[start..last,step]
[1927..1939], [x..y,z], [(11).pow(x)..(11).pow(x) + one])){
sum+=j.abs(); /* add absolute value of J */
if(prod.abs()<(2).pow(27) and j!=0) prod*=j; /* PROD is small enough & J */
}
/* SUM and PROD are used for verification of J incrementation */
println("sum = %,d\nprod = %,d".fmt(sum,prod));
Output:
sum  = 348,173
prod = -793,618,560