Python 判断一个数是否为质数

一个质数是大于1且不是两个较小的自然数相乘的数。任何大于1且只有两个因子（1和这个数本身）的整数称为质数。

假设以下是我们的输入：

输出结果应如下所示 –

Prime Number

检查一个数字是否为质数

让我们使用for循环检查一个数字是否为质数

示例

# Number to be checked for prime

n = 5

# Check if the number is greater than 1

if n > 1:
    for i in range(2, int(n/2)+1):
        if (n % i) == 0:
            print(num, "is not a prime number")
        break
    else:
        print(n, "is a prime number")
# If the number is less than 1, its also not a prime number.
else:
    print(n, "is not a prime number")

输出

5 is a prime number

使用sqrt()函数检查一个数是否为质数

让我们使用sqrt()函数来检查一个数是否为质数。

示例

from math import sqrt

# Number to be checked for prime
n = 9

flag = 0

if(n > 1):
    for k in range(2, int(sqrt(n)) + 1):
        if (n % k == 0):
            flag = 1
        break
    if (flag == 0):
        print(n," is a Prime Number!")
    else:
        print(n," is Not a Prime Number!")
else:
    print(n," is Not a Prime Number!")