Difference between revisions of "While"
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end; | end; | ||
end. | end. | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | |||
+ | |||
+ | You can use <syntaxhighlight lang="pascal" inline>Continue</syntaxhighlight> to jump to the end of the loop. | ||
+ | In the example below all values from 1 to 10 are printed, except 5. | ||
+ | <syntaxhighlight lang="pascal" line highlight="9"> | ||
+ | program whileDemo(input, output, stderr); | ||
+ | var | ||
+ | i:integer=0; | ||
+ | begin | ||
+ | while true do | ||
+ | begin | ||
+ | inc(i); | ||
+ | if i>10 then break; | ||
+ | if i=5 then continue; | ||
+ | writeLn(i); | ||
+ | end; | ||
+ | end; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
Revision as of 09:54, 4 January 2023
│
Deutsch (de) │
English (en) │
suomi (fi) │
français (fr) │
русский (ru) │
while
in conjunction with do
repeats a statement as long as a condition evaluates to true
.
The condition expression is evaluated prior each iteration, determining whether the following statement is executed.
This is the main difference to a repeat … until
-loop, where the loop body is executed at any rate, but succeeding iterations do not necessarily happen, though.
The following example contains unreachable code:
1program whileFalse(input, output, stderr);
2
3begin
4 while false do
5 begin
6 writeLn('never gets printed');
7 end;
8end.
You usually use while
-loops where, in contrast to for
-loops, a running index variable is not required, the statement executed can't be deduced from an index that's incremented by one, or to avoid a break
-statement (which usually indicates bad programming style).
1program whileDemo(input, output, stderr);
2
3var
4 x: integer;
5begin
6 x := 1;
7
8 // prints non-negative integer powers of two
9 while x < high(x) div 2 do
10 begin
11 writeLn(x);
12 inc(x, x); // x := x + x
13 end;
14end.
You can use Continue
to jump to the end of the loop.
In the example below all values from 1 to 10 are printed, except 5.
1program whileDemo(input, output, stderr);
2var
3 i:integer=0;
4begin
5 while true do
6 begin
7 inc(i);
8 if i>10 then break;
9 if i=5 then continue;
10 writeLn(i);
11 end;
12end;
see also
Keywords: begin — do — else — end — for — if — repeat — then — until — while