一、字符串常見操作（重點）

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1.

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2.字符串無法修改

#錯誤示范
str1="djskds"
str1[2]="3"

3.

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str1="abcand"
# 輸出3
print(str1.index("and"))

4.

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str1="abcand"
newStr=str1.replace("and","sel")
print(newStr)

5.

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str2="a b c d e"
print(str2.split(" "))

6.

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str2=" a b c d e "
print(str2.strip())
str2="12a b c d e12"
print(str2.strip("12"))

7.?

str2=" a b c d e "
print(str2.count(" "))

str2=" a b c d e "
print(len(str2))

二、序列容器切片（重點）

list=[1,2,3,4,5,6,7,8,9,10]
# 針對List進行切片 不包括4這個結尾
print(list[0:4])
# 起始留空默認從頭開始 結尾留空默認到末尾
print(list[:])
# 起始留空默認從頭開始 結尾留空默認到末尾（包含最后一個，也就是全部了） 但是間隔要為2
print(list[::2])
# 起始留空默認從頭開始 結尾留空默認到末尾 但是間隔要為-1 這時候就是要逆著取，相當于倒序輸出
print(list[::-1])
# 從三開始到1結束 不包括1 下標間隔為-1
print(list[3:1:-1])
# 逆序 下標為-2
print(list[::-2])
#輸出
[1, 2, 3, 4]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[1, 3, 5, 7, 9]
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
[4, 3]
[10, 8, 6, 4, 2]

三、集合

my_set={1,1,2,3,3,3,4,5,5,5,5,5,6,7,7,8,9,9,9,9,9,10}
print(my_set)#out
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

1.

2.

#添加后，該元素的位置也是不固定的，以及添加相同的元素也會自己去重
my_set={"xxx","yyy","zzzz","aaaa"}my_set.add("dddd")print(my_set)

3.

my_set={"xxx","yyy","zzzz","aaaa"}my_set.remove("aaaa")print(my_set)

4.

my_set={"xxx","yyy","zzzz","aaaa"}print(my_set.pop())

5.

6.

my_set={"xxx","yyy","zzzz","aaaa"}my_set2={"xxx"}print(my_set.difference(my_set2))#out
{'yyy', 'aaaa', 'zzzz'}

7.

my_set={"xxx","yyy","zzzz","aaaa"}my_set2={"xxx"}print(my_set.difference_update(my_set2))
#out
{'yyy', 'aaaa', 'zzzz'}
#就是消除兩個不同集合共有的

8.

my_set={"xxx","yyy","zzzz","aaaa"}my_set2={"xxx","yyy","xxx"}
print(my_set.union(my_set2))

9.去重后的長度

10.

#每次循環遍歷的順序都不一樣
my_set={"xxx","yyy","zzzz","aaaa"}for x in my_set:print(x)

三、字典（重點，后端返回的json格式等數據，經常需要用到）

1.key不能重復，否則取出來的值會被覆蓋

my_dick={"zs":90,"ls":80,"ww":70}
print(my_dick["zs"])

2.這個鍵和值都是不受限，除了key不能是字典

my_dick={"zs":{"math":30,"chinese":44,"English":50},"lssi":{"math":330,"chinese":443,"English":530},"ww":{"math":330,"chinese":434,"English":503}}
print(my_dick["zs"])
print(my_dick["zs"]["math"])
#out
{'math': 30, 'chinese': 44, 'English': 50}
30

3.

4.

my_dick={"zs":66,"lssi":77,"ww":55}
my_dick["zhaoliu"]=5
print(my_dick){'zs': 66, 'lssi': 77, 'ww': 55, 'zhaoliu': 5}

5.

my_dick={"zs":66,"lssi":77,"ww":55}
my_dick["zs"]=5
print(my_dick)
{'zs': 5, 'lssi': 77, 'ww': 55}

6.

my_dick={"zs":66,"lssi":77,"ww":55}
my_dick.pop("zs")
print(my_dick)
{'lssi': 77, 'ww': 55}

7.

my_dick={"zs":66,"lssi":77,"ww":55}print(my_dick.keys())
dict_keys(['zs', 'lssi', 'ww'])

8.遍歷字典

#方法一：
my_dick={"zs":66,"lssi":77,"ww":55}
keys1=my_dick.keys()
for key in keys1:print(my_dick[key])
#方法二：直接遍歷字典，然后以key名稱作為臨時變量，字典自己會去識別這個變量名
for key in my_dick:print(my_dick[key])
66
77
55

9.