python字典

   =============================================================字典======================================================

  

dict={
    'name':'章元领',
    'age':'19',
    'host':'www.cnblogs.com/Justice-V'

}
print(dict.get('age3',"没有此单词"))
#dict.get(self,key,default)
 key：搜索的键,例如dict的name
 default:如果搜索不到,那么返回default的内容


=============================================字典推导====================================================

1.生成10个链接,以1~10个数字作为键,以键为页号的url作为值
    urls_d={i:"www.xyz.com/?page={}".format(i) for i in range(1,11)}
    
结果:
 {1: 'www.xyz.com/?page=1', 2: 'www.xyz.com/?page=2', 3: 'www.xyz.com/?page=3', 4: 'www.xyz.com/?page=4', 
   5: 'www.xyz.com/?page=5', 6: 'www.xyz.com/?page=6', 7: 'www.xyz.com/?page=7', 8: 'www.xyz.com/?page=8', 
   9: 'www.xyz.com/?page=9', 10: 'www.xyz.com/?page=10'}
==========================================
【2】可以使用字典的items()方法对字典进行循环遍历,每次可以同时获得键和值;或者可以使用keys()方法对键进行遍历，每次可以利用键获得相应的值。两种方法类似。下面是两种方法的对比。

urls_d={i:"www.xyz.com/?page={}".format(i) for i in range(1,11)}   【第一种】
for key,val in urls_d.items():
    print(key,val)

urls_d={i:"www.xyz.com/?page={}".format(i) for i in range(1,11)}  【第二种】
for key in urls_d.keys():
    print(key,urls_d[key])