除了1 和它本身这两个数之外,不能被其他正整数整除的数叫做指数,即 prime number. 1 不是质数, 所以判断时,我们从2 开始。
对某个数n从2开始遍历,to(n-1),若能被其中某个数整除,则说明该数不是质数;
否则,说明是质数。
def prime_judge(n): if int(n) != n | n < 2: print("n is not a prime!") return else: for i in range(2,n): if n % i == 0: print("%d is not a prime, it can be divided by %d"%(n, i)) break #else special usage!!! else: print("%d is a prime number."%(n)) #another method def prime_judge2(n): if int(n) != n | n < 2: print("n is not a prime!") return else: for i in range(2,n): if n % i == 0: print("%d is not a prime, it can be divided by %d"%(n, i)) break else: pass if i == (n-1): print("%d is a prime number."%(n)) prime_judge2(15)