Python Basic introduction （ A full set of nanny level tutorials ）

Chapter two

Section 15 ： Basic operation of dictionary

Look up the dictionary
increase

dic = dict()

dic['jay'] = " Jay Chou "
dic[1] = 123
print(dic)

modify
here , It's already in the dictionary jay. At this time, the modification operation is executed

dic['jay'] = " Kunling "  #  here ,  It's already in the dictionary jay.  At this time, the modification operation is executed 
print(dic)

setdefault
Set the default value . If it had existed before tom 了 . setdefault It doesn't work

dic.setdefault("jay", " soup with pepper ")  #  Set the default value .  If it had existed before tom 了 . setdefault It doesn't work 
print(dic)

Delete
according to key To delete

dic.pop("jay")  #  according to key To delete 
print(dic)

Inquire about
dic [ ] If key non-existent . The program will report an error . When you are sure of your key No problem , It can be used
get If key non-existent . Program return None. When unsure of your key When . It can be used

print(dic['jay10010'])  #  If key non-existent .  The program will report an error .  When you are sure of your key No problem ,  It can be used 
print(dic.get('jay10086'))  #  If key non-existent .  Program return None.  When unsure of your key When .  It can be used 

None Pure is empty , It means nothing

a = None  #  Pure is empty ,  It means nothing 
print(type(a))

Example :

dic = {
    
    " Zhao si ": " He can crook his mouth ",
    " Lennon ": " The old ,  Old four ...",
    " Bigfoot ": " Have sex with this and that ",
    " Big head ": " act blindly ....",
}
name = input(" Please enter the name of the people in our village you want to know : ")
val = dic.get(name)
if val is None:
    print(" There is no such person in our village ~~~")
else:
    print(val)

When you enter, you cannot find , Output none There is no such person in our village .