python中判断数字是否为质数的实例讲解

def isprime(a):
 if isinstance(a,int)==False:
  return False
 if a<=1:
  return False
 if a==2:
  return True
 flag=1
 x=int(pow(a,0.5))+1
 for n in range(2,x):
  if a%n == 0:
   flag=0
   break
 if flag==1:
  return True
 else:
  return False

# -*- coding: UTF-8 -*-
 
# Filename : test.py
# author by : www.runoob.com
 
# Python 程序用于检测用户输入的数字是否为质数
 
# 用户输入数字
num = int(input("请输入一个数字: "))
 
# 质数大于 1
if num > 1:
  # 查看因子
  for i in range(2,num):
    if (num % i) == 0:
      print(num,"不是质数")
      print(i,"乘于",num//i,"是",num)
      break
  else:
    print(num,"是质数")
    
# 如果输入的数字小于或等于 1，不是质数
else:
  print(num,"不是质数")