Python基础
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highlight: Python基础
Python 是一种解释型、面向对象、动态数据类型的高级程序设计语言。
Python 由 Guido van Rossum 于 1989 年底发明，第一个公开发行版发行于 1991 年。像 Perl 语言一样, Python 源代码同样遵循 GPL(GNU General Public License) 协议。官方宣布，2020 年 1 月 1 日， 停止 Python 2 的更新。Python 2.7 被确定为最后一个 Python 2.x 版本。
一. 变量类型
在Python中没有和C , Java一样要求对于基本变量的定义所以只要定义其变量名称直接赋值就行，类似于默认javascript中的var只是作为一个声明，这是一个变量。
var0 = 'a'
print(var0)
pass
var1 = "hr"
print(var1)
pass
var2 = 10
print(var2)
pass
var3 = 100000.00
print(var3)
pass
varTrue = True
varFalse = False
if varTrue:
print("bool值True is True")
else:
print("bool值false is True")
pass
if not varFalse:
print("bool值True is False")
else:
print("bool值false is False")
pass
str = "你是谁老豆？"
print(str[:2])
print(str[2:len(str) - 1])
pass
list1 = ['python', 'java', 1996, 2020]
list2 = [1, 2, 3, 4, 5]
list3 = ["a", "b", "c", "d"]
print(list1)
print(list1 + list2)
list3.append(1)
list3.append(2)
list3.append(3)
print(list3)
list3.insert(2, 3)
list3.insert(2, list1)
print(list3)
del list3[1]
print(list3)
list3.remove("c")
print(list3)
pass
a = (1, 2, 3, 4, 5, "1", "2")
print(a)
pass
a = {"key1": "value1", "key2": "value2"}
print(a)
print(a["key1"])
print(a.get("key1"))
a["key2"] = "my love"
print(a["key2"])
del a['key2']
print(a)
pass
二. 算术运算符
| 运算符 | 描述 |
|---|
| + | a值 + b值 |
| - | a值 - b值 |
| * | a值 * b值 |
| / | a值 / b值 |
| % | a值 % b值 |
| ** | a值 ** b值 |
| // | a值 // b值 |
int1 = 2
int2 = 6
int3 = 8
int4 = 10
int5 = 3
print("int加法: ", int1 + int2)
print("int减法: ", int4 - int2)
print("int乘法: ", int3 * int2)
print("int除法: ", int4 / int1)
print("int取模: ", int4 % int5)
print("int幂等: ", int1 ** int2)
print("int整除: ", int4 // int5)
pass
double1 = 10.00
double2 = 20.10
double3 = 30.20
double4 = 40.30
print("double加法：", double1 + double2)
print("double减法：", double4 - double3)
print("double乘法：", double4 * int2)
print("double除法：", double4 / int1)
print("double取模：", double4 / double1)
print("double幂等: ", double4 ** int2)
print("double整除: ", double4 // int5)
三. 条件语句与循环语句
常用语句：
1. if...else...
2. while
3. for
4. break，continue
a = 0
if a == 0:
print("我等于0哦！")
else:
print("我不等于0哦！")
pass
a = 0
b = 0
while a == 0:
print("我来了第", b, "次！")
b = b + 1
a = 0
while a < 5:
print("我是", a, "号！")
a = a + 1
a = 0
exact = []
not_exact = []
while a < 10:
if a % 2 == 0:
exact.append(a)
else:
not_exact.append(a)
a = a + 1
else:
print("这个循环我结束了！")
print("能被被整除的数：", exact)
print("不能被被整除的数：", not_exact)
pass
a = 0
exact = []
while a < 10:
if a % 2 == 0:
exact.append(a)
else:
a = a + 1
continue
a = a + 1
print("能被被整除的数 continue ：", exact)
pass
a = 0
exact = []
while a < 10:
if a % 2 == 0:
exact.append(a)
else:
a = a + 1
break
a = a + 1
print("能被被整除的数 break ：", exact)
pass
a = [1, 2, 3, "4", 5, True]
for b in a:
print(b)
pass
a = [1, 2, 3, "4", 5, True, 9, '10']
b = False
d = []
for c in a:
if c == True:
b = True
continue
d.append(c)
print("含有bool值吗? ", b)
print("不含bool值的数组：", d)
pass
四. 日期与时间
import time
pass
ticks = time.time()
print("当前时间戳为:", ticks)
pass
localtime = time.localtime(time.time())
print("本地时间为 :", localtime)
pass
localtime = time.asctime(time.localtime(time.time()))
print("本地时间为 :", localtime)
pass
print(time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
print(time.strftime("%a %b %d %H:%M:%S %Y", time.localtime()))
a = "Sat Mar 28 22:24:24 2016"
print(time.mktime(time.strptime(a, "%a %b %d %H:%M:%S %Y")))
pass
import calendar
cal = calendar.month(2020, 1)
print("输出2020年1月份的日历:")
print(cal)
pass
五. 函数与模块（Module）
1. 函数是组织好的，可重复使用的，用来实现单一，或相关联功能的代码段。
2. 函数能提高应用的模块性，和代码的重复利用率。
3. 模块 能定义函数，类和变量，模块里也能包含可执行的代码。
def test_function(str):
if str % 2 == 0:
return str
else:
return False
str = 3
print(test_function(str))
import dbtest
print(dbtest.test_function(2))
pass
六. File文件使用方法
str = input("请输入：")
print("最终值为：", str)
pass
fo = open("D:\\桌面\\test.txt", "w+", -1)
print("文件名: ", fo.name)
print("是否已关闭 : ", fo.closed)
print("访问模式 : ", fo.mode)
pass
fo.write("当一个文件对象的引用被重新指定给另一个文件时，Python 会关闭之前的文件。用 close（）方法关闭文件是一个很好的习惯。")
print("写入成功！")
pass
var = fo.read(10)
print("文件内容：", var)
pass
print("文件位置：", fo.tell())
pass
fo.close()
print("已关闭")
pass
import os
var1 = "D:\\桌面\\test.txt"
var2 = "D:\\桌面\\test2.txt"
os.rename(var1, var2)
print(var1, "已重新命名", var2)
pass
os.remove(var2)
print(var2, "，该文件已被删除！")
pass
var3 = "D:\\桌面\\"
os.chdir(var3)
print("已跳转目录至：", var3)
pass
var4 = "123456789"
print("创建成功！")
pass
var5 = var3+var4
print(var3, var4, "，该文件已被删除！")
pass
var6 = "D:\\桌面\\test123.txt"
fo2 = open(var6, "w+")
line_read = fo2.readline(10)
print("读取的字符串为: %s" % line_read)
a = 0
while 10 > a:
fo2.writelines("我开始喽！")
a += 1
print("录入成功！")
pass
ret = fo2.isatty()
print(ret)
fo2.flush()
fo2.close()
pass
