Loops/Wrong ranges: Difference between revisions
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* [[Loops/Wrong ranges]]
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=={{header|Ada}}==
Ada uses the concept of a range extensively, both in the definition of programmer-defined scalar types and subtypes and also in the iteration of arrays. In Ada a range is defined in the Ada 2012 Language Reference Manual as
''A range has a lower bound and an upper bound and specifies a subset of the values of some scalar type (the type of the range). A range with lower bound L and upper bound R is described by “L .. R”. If R is less than L, then the range is a null range, and specifies an empty set of values. Otherwise, the range specifies the values of the type from the lower bound to the upper bound, inclusive.''
The following solution follows the logic of a range as specified in the task description.
<lang ada>with Ada.Text_IO; use Ada.Text_IO;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
with Ada.Text_IO.Unbounded_IO; use Ada.Text_IO.Unbounded_IO;
procedure Main is
procedure print_range(start : integer; stop : integer; step : integer) is
Num : Integer := start;
begin
Put("Range(" & start'Image & ", " & stop'image &
", " & step'image & ") => ");
if stop < start then
Put_Line("Error: stop must be no less than start!");
elsif step not in positive then
Put_Line("Error: increment must be greater than 0!");
elsif start = stop then
Put_Line(start'image);
else
while num <= stop loop
Put(num'Image);
num := num + step;
end loop;
New_Line;
end if;
end print_range;
type test_record is record
start : integer;
stop : integer;
step : integer;
comment : unbounded_string := null_unbounded_string;
end record;
tests : array(1..9) of test_record :=
( 1 => (-2, 2, 1, To_Unbounded_String("Normal")),
2 => (-2, 2, 0, To_Unbounded_String("Zero increment")),
3 => (-2, 2, -1, To_Unbounded_String("Increments away from stop value")),
4 => (-2, 2, 10, To_Unbounded_String("First increment is beyond stop value")),
5 => (2, -1, 1, To_Unbounded_String("Start more than stop: positive increment")),
6 => (2, 2, 1, To_Unbounded_String("Start equal stop: positive increment")),
7 => (2, 2, -1, To_Unbounded_String("Start equal stop: negative increment")),
8 => (2, 2, 0, To_Unbounded_String("Start equal stop: zero increment")),
9 => (0, 0, 0, To_Unbounded_String("Start equal stop equal zero: zero increment")));
begin
for test of tests loop
Put(Test.Comment); Put(" : ");
print_range(test.start, test.stop, test.step);
New_line;
end loop;
end Main;</lang>
{{out}}
<pre>
Normal : Range(-2, 2, 1) => -2-1 0 1 2
Zero increment : Range(-2, 2, 0) => Error: increment must be greater than 0!
Increments away from stop value : Range(-2, 2, -1) => Error: increment must be greater than 0!
First increment is beyond stop value : Range(-2, 2, 10) => -2
Start more than stop: positive increment : Range( 2, -1, 1) => Error: stop must be no less than start!
Start equal stop: positive increment : Range( 2, 2, 1) => 2
Start equal stop: negative increment : Range( 2, 2, -1) => Error: increment must be greater than 0!
Start equal stop: zero increment : Range( 2, 2, 0) => Error: increment must be greater than 0!
Start equal stop equal zero: zero increment : Range( 0, 0, 0) => Error: increment must be greater than 0!
</pre>
=={{header|ALGOL W}}==
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