python基础

Posted 2021-01-09 萌萌~哒

一、list循环

import copy
# l = [1,1,1,2,3,4,5]
#     #1 1,2,3,4,5
#     #0 1 2 3 4 5 6
# # l2=[1,1,1,2,3,4,5]
# # l2 = copy.deepcopy(l)# 深拷贝
#
# l2 = l #浅拷贝
# #l2 = l.copy() #浅拷贝
#
# print(id(l))
# print(id(l2))
# for i in l2:
#     if i%2!=0:
#         l.remove(i)
# print(l)
#循环删list的时候，会导致下标错位，结果是不对的

a=‘tanailing‘
b = a
a=‘niuniu‘

print(a)
print(b)

2、非空即真、非零即真（重要）

#非空即真，非零即真

name = input(‘请输入名称：‘).strip()
#name=‘abc‘
#a=‘‘
#l=[]
#d={}
#t=()
#b=None
name = int(name)
if name:
    print(‘输入正确‘)
else:
    print(‘name不能为空‘)

三、函数

def my(name,sex):
    #位置参数，必填
    #默认值参数
     #函数体
    return name

def db_connect(ip,port=3306):
    print(ip,port)

# db_connect(‘118.24.3.40‘,3307)
# db_connect(‘118.24.3.40‘)
import json
def op_file_tojson(file_name,dic=None):
    if dic:
        with open(file_name,‘w‘,encoding=‘utf-8‘) as fw:
            json.dump(dic,fw)
    else:
        f = open(file_name,encoding=‘utf-8‘)
        content = f.read()
        if content:
            res = json.loads(content)
        else:
            res = {}
        f.close()
        return res


res = db_connect(‘118.24.3.40‘,3307)

def my2():
    for i in range(50):
        return i

def my3():
    a = 1
    b = 2
    c = 3
    return a,b,c

b,c,d = my3()
s = my3()
# print(b,c,d)
# print(s)

# a,b,c = 1,2,3
#
# a = b = c = 1

# def my4(s:str,d:dict):
#     print(s)
#     print(d)
#
# my4(134,‘abcd‘)


#return 有2个作用
#1、结束函数，只要函数里面遇到return，函数立即结束运行
#2、返回函数处理的结果