51 lines
1.4 KiB
Plaintext
51 lines
1.4 KiB
Plaintext
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(*
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adapted to Oberon-07 by 0CodErr, KolibriOS team
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*)
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(* This was taken from the CRITICAL MASS MODULA-3 examples *)
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(* The "Sieve" program demonstrates the use of arrays,
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loops and conditionals. *)
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MODULE Sieve;
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IMPORT In, Out, Console;
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(* Search in interval 2 to 1000 for prime numbers. *)
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CONST
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LastNum = 1000;
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(* "prime" is an array of booleans ranging from 2 to "LastNum". *)
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VAR
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prime: ARRAY LastNum + 2 OF BOOLEAN;
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i, j: INTEGER;
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BEGIN
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Console.open;
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Out.String("Primes in range 2.."); Out.Int(LastNum, 1); Out.Char(":"); Out.Ln;
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(* Initialize all elements of the array to "TRUE".
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(Note that we could have initialized the array during
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the assignment.) *)
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FOR i := 2 TO LastNum DO
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prime[i] := TRUE
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END;
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(* Loop through all integers between 2 and "LastNum". Print each prime
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number, starting from 2 and mark all numbers that are divisible by
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that prime number to "FALSE". Repeat the step until we've exhausted
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all the numbers in the interval.*)
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FOR i := 2 TO LastNum DO
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IF prime[i] THEN
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Out.Int(i, 3);
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Out.Char(" ");
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FOR j := i TO LastNum DO
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IF j MOD i = 0 THEN
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prime[j] := FALSE
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END
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END
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END
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END;
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Out.Ln; In.Ln;
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Console.exit(TRUE)
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END Sieve.
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