021.Python的内置函数

res = abs(-9.9867)
print(res)

[root@node10 python]# python3 test.py
9.9867

res = round(3.5)
print(res)
res = round(12.5)
print(res)

[root@node10 python]# python3 test.py
4
12

listvar = [1,2,34,34,43,32,5]
total = 0
for i in listvar:
        total += i
print(total)

res = sum(listvar)
print(res)

[root@node10 python]# python3 test.py
151
151

listvar = [1,2,34,34,43,32,5]
res = max(listvar)
print(res)

[root@node10 python]# python3 test.py
43

listvar = [1,2,34,34,43,32,5]
res = min(listvar)
print(res)

[root@node10 python]# python3 test.py
1

listvar = [1,2,34,34,43,32,5]
listvar.sort()
print(listvar)
res_min = listvar[0]
res_max = listvar[-1]
print(res_min)
print(res_max)

[root@node10 python]# python3 test.py
[1, 2, 5, 32, 34, 34, 43]
1
43

listvar = [("张三",45),("李四",38),("王五",18),("田七",120)]
def func(n):
    #("张三",45)
    return n[-1]
res = min(listvar,key=func)
print(res)

[root@node10 python]# python3 test.py
(‘王五‘, 18)

("王五",18 扔到func当中  return 18
首先把("张三",45) 扔到func当中  return 45
("李四",38) 扔到func当中  return 38
("田七",120)  扔到func当中  return 120
按照右侧实际年龄进行排序,找出最小的那个数,直接把元组返回.

res = pow(2,3)
print (res)
res = pow(4,20)
print(res)
‘‘‘pow(可以接受第三个可选参数 , 第三个参数是用来取余的)‘‘‘
res=  pow(2,3,3)
print(res)

[root@node10 python]# python3 test.py
8
1099511627776
2

res = range(10)
print(res)
for i in range(10):
    print(i)
for i in range(1,8):
    print(i)
for i in range(1,16,3):
    print(i)

for i in range(10,0,-1):
    print(i)

[root@node10 python]# python3 test.py
range(0, 10)
0
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
1
4
7
10
13
10
9
8
7
6
5
4
3
2
1

res = bin(15)
print(res)

[root@node10 python]# python3 test.py
0b1111

res = oct(8)
print(res)

[root@node10 python]# python3 test.py
0o10

res = hex(16)
print(res)

[root@node10 python]# python3 test.py
0x10

res  = chr(97)
print(res)

[root@node10 python]# python3 test.py
a

res = ord("A")
print(res)

[root@node10 python]# python3 test.py
65

res = "print(123)"
print(res)
eval(res)
res = "print(‘sdfsdf‘)"
print(res)
eval(res)
res = "print(\"sdfsdf\")"
print(res)
eval(res)

[root@node10 python]# python3 test.py
print(123)
123
print(‘sdfsdf‘)
sdfsdf
print("sdfsdf")
sdfsdf

res = """
for i in range(10):
        print(i)
"""
# 要注意小心sql注入 delete from 数据 where id = 1 exec或者eval两个函数慎用
exec(res)

[root@node10 python]# python3 test.py
0
1
2
3
4
5
6
7
8
9

listvar = [1,2,3]
res = repr(listvar)
print(res,type(res))
strvar = "123"
print(repr(strvar))
strvar = "111\n\t\r"
print(repr(strvar))

[root@node10 python]# python3 test.py
[1, 2, 3] <class ‘str‘>
‘123‘
‘111\n\t\r‘

字典的键 和 集合当中的值 需要使用哈希算法
哈希算法在存储上是无序的散列,经过计算之后会产生具有固定长度的唯一值

res1 = "今天天气好"
res2 = "今天天气好"
res3 = "132"
print(hash(res1))
print(hash(res2))
print(hash(res3))

[root@node10 python]# python3 test.py
-8085451974024421996
-8085451974024421996
-5108487044744349521