素数(质数)的求法。若求
N内的素数,可用
N的平方根以内的素数倍数逐个筛掉,余下的便是所求的素数。源程序
ex9_1.prg如下:
SET TALK OFF
INPUT " 请输入自然数 N = " TO N
?
? " 从1至 " + STR(N) + " 间的所以质数 "
l = 0
i = 3
DO WHILE i <= N
j = INT(SQRT(i))
k = 3
DO WHILE k <= j
l = i - INT(i / k) * k
IF l = 0
EXIT
ENDIF
k = k + 1
ENDDO
IF l <> 0
?? i
ENDIF
i = i + 2
ENDDO
RETU
INPUT " 请输入自然数 N = " TO N
?
? " 从1至 " + STR(N) + " 间的所以质数 "
l = 0
i = 3
DO WHILE i <= N
j = INT(SQRT(i))
k = 3
DO WHILE k <= j
l = i - INT(i / k) * k
IF l = 0
EXIT
ENDIF
k = k + 1
ENDDO
IF l <> 0
?? i
ENDIF
i = i + 2
ENDDO
RETU