howie.for

来自「开放源码的编译器open watcom 1.6.0版的源代码」· FOR 代码 · 共 30 行

* This program computes the prime numbers between 1 and 10000
* using the Sieve of Eratosthenes algorithm.

      IMPLICIT NONE
      INTEGER UPBOUND
      PARAMETER (UPBOUND=10000)
      INTEGER I, K, PRIMES
      LOGICAL*1 NUMBERS(2:UPBOUND)
      CHARACTER*11 FORM
      PARAMETER (FORM='(A,I5,A,I5)')
      COMPLEX   X
      
      DO I = 2, UPBOUND
	  NUMBERS(I) = .TRUE.
      ENDDO
      PRIMES = 0
      X = (1,0) + (1,-1) 
      DO I = 2, UPBOUND
	  IF( NUMBERS(I) )THEN
	      PRIMES = PRIMES + 1
	      DO K = I + I, UPBOUND, I
		  NUMBERS(K) = .FALSE.
	      ENDDO
	  ENDIF
      ENDDO
      PRINT FORM, 'The Number of Primes between 1 and ', UPBOUND,
     1		  ' are: ', PRIMES
      END