python爬虫入门

Posted 2021-12-24 playforever

if 条件语句

a=3
if a>3:
    print("ok")
elif a==3:
    print("no")
else:
    print("dagag")

循环语句：
list1=["aaa","eee"];
i=0;
while i<len(list1):
    print(list1[i])
    i+=1
for it in list1:
    print(it)

 

类

class Person:
    def _init_(self,name,age):
        self.name=name
        self.age=age
       
obj1=Person(‘tian‘,20)
print(obj1.name)
 报错如下：

TypeError                                 Traceback (most recent call last)
<ipython-input-50-2187ba575e0c> in <module>
      4         self.age=age
      5 
----> 6 obj1=Person(‘tian‘,20)
      7 print(obj1.name)
      8 

TypeError: Person() takes no arguments

经查发现 类的构造方法 init左右都应该有两个_
修改如下：
class Person:
    def __init__(self,name,age):
        self.name=name
        self.age=age
        
obj1=Person(‘tian‘,20)
print(obj1.name)