python循环&判断&断言

1.循环判断：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
'''
Created on 2017年9月18日

'''
#________________________for循环算出质数________________________________________
for num in range(10,20):  # 迭代 10 到 20 之间的数字
   for i in range(2,num): # 根据因子迭代
      if num%i == 0:      # 确定第一个因子
         j=num/i          # 计算第二个因子
         print ('%d 等于 %d * %d' % (num,i,j))
         continue            # 跳出当前循环
   else:                  # 循环的 else 部分
      print (num, '是一个质数')

#_________________循环&判断____________________________________________________
for letter in 'Python':     # First Example
   if letter == 'h':
      break
   print ('Current Letter :', letter)

var = 10                    # Second Example
while var > 0:
   print ('Current variable value :', var)
   var = var -1
   if var == 5:
      break

print ("Good bye!")

#换行接着写代码
kkk='fueifjiej' \
    'fije';chen=kkk.split();print (chen)

print("\\t")
print(r"\t")


#.....................break跳转(跳出循环语句)......................
'''
a = 2
b = 2
sum =0
for i in range(1,10):#3表示步值(间隔值)
    print 'i=',i
    sum+=i
    if sum==6:
        print 'sum=',sum
    else:
        print'滚蛋色狼'
        break
        print 'hahahhahahahahhah'
        print '123123123'

print '一切将以结束'

'''

#.............continue跳转(跳出当前一次循环)................
a = 2
b = 2
sum =0
for i in range(1,10):#3表示步值(间隔值)
    print('i=',i)
    sum+=i
    if sum==6:
        print ('sum=',sum)
    else:
        print('滚蛋色狼')
        continue
        print ('hahahhahahahahhah')
print (R'一切\t将以结束')#打印原始字符\t

#________________for循环参数_______________________
for i in range(10,1,-1): #-1表示倒序开始
    print(i)

for a in range(1,10,2): #2表示步长值/间隔值
    print(a)

 

2.assert使用

在开发一个程序时候，与其让它运行时崩溃，不如在它出现错误条件时就崩溃（返回错误）。这时候断言assert 就显得非常有用

#!/usr/bin/env python
# -*- coding: utf-8 -*-

a_str = 'this is a string'
b=type(a_str)
print('a_str类型为',b)
#断言是否等于str(不符合就报异常)
assert b== str

 

 3.多条件if判断

a=1;b=2;c=3;d=4
a1=1;b1=2;c1=3;d1=4

#逐个比较的方式来判断
if a == a1 and b == b1 and c == c1 and d == d1:
    print("a=a1, b=b1, c=c1, d=d1")
else:
    print("a, b, c, d不等于a1, b1, c1, d1")

#使用元组比较判断
if (a, b, c, d) == (a1, b1, c1, d1):
    print("a=a1, b=b1, c=c1, d=d1")
else:
    print("a, b, c, d不等于a1, b1, c1, d1")
    
# 判断chen22是否在a、b、c(满足一个条件即可)
if "chen22" in (a, b, c):
    print("True")
else:
    print("False")

 

 4.通过对象完成变量判断

#!/usr/bin/python
# -*- coding: UTF-8 -*-
class Student:
    def __init__(self, student_id, name, age):
        self.student_id = student_id
        self.name = name
        self.age = age

    def __eq__(self, other):
        if isinstance(other, Student):
            return (self.student_id == other.student_id and
                    self.name == other.name and
                    self.age == other.age)
        return False


if __name__ == "__main__":
    student1 = Student("001", "Alice", 18)#参数可以写成变量
    student2 = Student("001", "Alice", 18)
    student3 = Student("002", "Bob", 20)

    print(student1 == student2)  # 输出 True
    print(student1 == student3)  # 输出 False

 

 5.多个变量通过list判断是否一致

#_______________________判断a==a1，b==b1，c==c1，d==d1_______________________________
a = ["chenwei","wei"]
b = "b"
c = "c"
d = {
"name":"点击量",
"historyBack":False,
"assetTypes":[
    {
        "operation":"DISABLE",
        "feed_delivery_search":"DISABLED"
    }
],
"flag":""
}



a1 = ["chenwei","wei"]
b1 = "b"
c1 = "c"
d1 = {
"name":"点击量",
"historyBack":False,
"assetTypes":[
    {
        "operation":"DISABLE",
        "feed_delivery_search":"DISABLED"
    }
],
"flag":""
}

#把变量分别放到list
strings = [a, b, c, d]
strings1 = [a1, b1, c1, d1]
are_equal = all(x == y for x, y in zip(strings, strings1))
print("判断多个变量相等:",are_equal)

 

 

 

相关连接：

https://blog.csdn.net/humanking7/article/details/45950781 ..............python中assert的使用