python基础之常用的公共方法

# len() 计算容器重元素个数
str1 = 'abcdefg'
list1 = [10, 20, 30, 40, 50]
t1 = (100, 200, 300, 400, 500)
s1 = {100, 200, 300, 400, 500}
dict1 = {'name': 'python', 'age': '18'}
print(len(str1))  # 7
print(len(s1))  # 5
print(len(list1))  # 5
print(len(t1))  # 5
print(len(dict1))  # 2
print(len(dict1.keys()))  # 2

# del 删除 del或del()
str1 = 'abcdefg'
list1 = [10, 20, 30, 40, 50]
t1 = (100, 200, 300, 400, 500)
s1 = {100, 200, 300, 400, 500}
dict1 = {'name': 'python', 'age': '18'}

# del str1
# print(str1)  # name 'str1' is not defined
# del(list1)
# print(list1)  # name 'list1' is not defined
# del(list1[0])
# print(list1)  # [20, 30, 40, 50]
# del dict1
# print(dict1)  #  name 'dict1' is not defined
# del dict1["name"]
# # print(dict1)  # {'age': '18'}

# max() 返回容器重最大值 min() 返回容器中最小值
str1 = 'abcdef'
list1 = [10, 20, 30, 40, 50]
print(max(str1))  # f
print(min(str1))  # a
print(max(list1))  # 50
print(min(list1))  # 10

# range() 生成从start到end的数字，步长为step,供for循环使用
# str1 = 'abcdefgijklmnopqwxyz'
for i in range(1, 10, 1):
    print(i)
# 1,3,5,7,9
for i in range(1, 10, 2):
    print(i)
# 0,1,2,3,4,5,6,7,8,9
for i in range(10):
    print(i)
# 如果不写开始默认从0开始
# 如果不写步长默认为1

# enumerate() 函数用于将一个可遍历的数据对象(列表，元组或字符串)
# 组合为一个索引序列同时列出数据和下表，一般用在for循环当中
# 语法 enumerate(可遍历对象， start=0)
list1 = ['a', 'b', 'c', 'd', 'e']
for i in enumerate(list1):
    print(i)

# 下标 值
# (0, 'a')
# (1, 'b')
# (2, 'c')
# (3, 'd')
# (4, 'e')

for i in enumerate(list1, start=1):
    print(i)
    
# (1, 'a')
# (2, 'b')
# (3, 'c')
# (4, 'd')
# (5, 'e')