1.for

# for可使用迭代器进行元素的访问
for item in 'HelloWord':
    print(item, end=' ')

2.while

Sum = 0
while Sum <= 50:  # 该循环公执行51次
    Sum += 1
print(Sum)  # 51

3.else的特殊用法

'''在for和while后面加else 当for和while正常退出时，else执行 
   如果遇到break没有执行完，则会跳过else里的内容
'''
for item in range(10):
    if item == 5:
        break
else:
    print("for执行完成")
'''while同理'''

4.list

1.创建列表

# 列表类似于数组，其中内容可以混用（内容为多种类型），list里可以添加内容为list的元素
# 创建方法
lst1 = ['abc', 123, 123.456, False, "字符串"]
print(lst1)
# 也包含三种属性
print('id:', id(lst1), end='\t')
print("type:", type(lst1), end='\t')
print("value:", lst1)
# 正索引从0开始， 负索引从-1到-n
print(lst1[0], lst1[-5])

2.添加元素

append() 函数

lst1 = ['abc', 123, 123.456, False, "字符串"]
lst1.append(123.456)  # 在list后追加内容  即可变长
print(lst1)  # ['abc', 123, 123.456, False, '字符串', 123.456]

insert函数

lst1 = ['abc', 123, 123.456, False, "字符串"]
lst1.insert(0, '789')  # 在指定位置插入元素
print(lst1)  # ['789', 'abc', 123, 123.456, False, '字符串']

extend() 函数

lst1 = [1, 2, 3, 4]
lst1.extend([10, 9, 8])  # 在末尾添加多个元素 参数类型：列表
print(lst1)  #  [1, 2, 3, 4, 10, 9, 8]

pop() 函数

lst1 = [0, 1, 2, 3, 4, 5, 6, 7]
lst1.pop(0)  # 根据索引移除元素
print(lst1)  # [1, 2, 3, 4, 5, 6, 7]

lst1 = [0, 1, 2, 3, 4, 5, 6, 7]
lst1.pop()  #  不指定参数，删最后一个
print(lst1)  # [0, 1, 2, 3, 4, 5, 6]

lst1 = [0, 1, 2, 3, 4, 5, 6, 7]  # 索引 ：0-7
lst1.pop(8)  #  索引越界报错  IndexError: pop index out of range

remove() 函数

lst1 = [0, 1, 2, 5, 4, 5, 6, 7]
lst1.remove(5)  # 移除列表里第一次遇到的该元素 参数：需移除的元素
print(lst1)  # [0, 1, 2, 4, 5, 6, 7]

lst1 = [0, 1, 2, 5, 4, 5, 6, 7]
lst1.remove(100)  # ValueError: list.remove(x): x not in list

clear() 函数

lst1 = [0, 1, 2, 3, 4, 5, 6, 7]
lst1.clear()  # 清除列表内的元素
print(lst1)  # []

del

lst1 = [0, 1, 2, 3, 4, 5, 6, 7]
del lst1  # 删除变量 其他类型的变量同样适用
print(lst1)  # NameError: name 'lst1' is not defined

切片操作

lst2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
# list[start : stop : step]  start默认0  stop默认maxsize-1  step 默认 1
# step为负数时，逆序输出，这时的start应从maxsize-1开始
print(lst2[::])  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
# start默认maxsize-1   stop默认0   step=-1 逆序输出
print(lst2[::-1])  # [19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
print(lst2[19::-2])  # [19, 17, 15, 13, 11, 9, 7, 5, 3, 1]
print(lst2[0:10:2])  # [0, 2, 4, 6, 8]

判断是否在列表中

lst2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
judge = 15 in lst2
print(judge)  # True

更改元素

lst2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
lst2[1:3] = [10, 20, 30]  # 把start到stop-1中间的元素切掉并用后面的list填充原来的位置  
print(lst2)  # [0, 10, 20, 30, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

# 删除 0-9
lst2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
lst2[0:10] = []  # 可替换为空列表
print(lst2)  # [10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

index函数

lst1 = ['abc', 123, 123.456, False, "字符串"]
index_123 = lst1.index(123)  # 查找索引 
print(index_123)  # 1

sort函数

lst3 = [8, 4, 6, 9, 7, 2, 1, 3, 0, 5, 11, 98, 46, 87, 13, 65, 99]
lst3.sort()  # 排序不产生新列表 
print(lst3)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 46, 65, 87, 98, 99]

lst3 = [8, 4, 6, 9, 7, 2, 1, 3, 0, 5, 11, 98, 46, 87, 13, 65, 99]
lst3.sort(reverse=True)  # 降序排序  默认False
print(lst3)  # [99, 98, 87, 65, 46, 13, 11, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

sorted函数

# 该函数为内置函数  会产生新列表 
lst3 = [8, 4, 6, 9, 7, 2, 1, 3, 0, 5, 11, 98, 46, 87, 13, 65, 99]
new_list = sorted(lst3, reverse=True)
print(lst3)  # [8, 4, 6, 9, 7, 2, 1, 3, 0, 5, 11, 98, 46, 87, 13, 65, 99]
print(new_list)  # [99, 98, 87, 65, 46, 13, 11, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

列表生成式

list = [i for i in range(1, 10)]
print(list)  # [1, 2, 3, 4, 5, 6, 7, 8, 9]

list = [i*2 for i in range(1, 10)]
print(list)  # [2, 4, 6, 8, 10, 12, 14, 16, 18]