Python基础语法1

# -*- coding: UTF-8 -*-print("Hello world")print("你好，世界")if False:    print("True")else:    print("false")import sysx = "python"sys.stdout.write(x + "\n")counter = 1000  # 整形miles = 100.0  # 浮点型name = "python"  # 字符串行print(counter)print(miles)print(name)'''Python有5个标准的数据类型Numbers（数字）String（字符串）List（列表）Tuple（元组）Dictionary（字典）'''"""用del语句删除一些对象的引用"""del counter"""Traceback (most recent call last):  File "E:/PythonProject/test/test3.py", line 36, in <module>    print(counter)NameError: name 'counter' is not defined"""# print(counter)   #执行 del  counter 后，如何再次打印counter的值，会出现上方的错误信息: name 'counter' is not defined'''python支持4种不同的数字类型int（有符号整型）long（长整型[也可以代表八进制和十六进制]）float（浮点型）complex（复数）形如a+b*i的数，其中a,b是实数，且b≠0,i² = - 1'''# 字符串截取str = "ilovepython"print(str)print(str[1:5])  # 截取第二个到第5个之间的字符print(str[0])  # 输出字符串第一个字符print(str[1:])  # 输出从第二个开始的字符串print(str * 2)  # 星号（*）是重复操作,输出字符串两次print(str + "TEST")  # 加号（+）是字符串连接运算符'''输出结果ilovepythonloveilovepythonilovepythonilovepythonilovepythonTEST'''# List列表截取(集合数据类型)list = ['adbce', 28.2, 867, 'john', 70.2]tinylist = [123, 'john']print(list[0])print(list[1:])print(list[1:4])print(list * 2)print(list + tinylist)'''输出结果adbce[28.2, 867, 'john', 70.2][28.2, 867, 'john']['adbce', 28.2, 867, 'john', 70.2, 'adbce', 28.2, 867, 'john', 70.2]['adbce', 28.2, 867, 'john', 70.2, 123, 'john']'''# Tuple元组,元组不能二次赋值，相当于可读List（列表）tuple = ('abcd', 786, 2.23, 'john', 70.2)tinytuple = (123, 'john')print(tuple)  # 输出完整元组print(tuple[0])  # 输出元组的第一个元素print(tuple[1:3])  # 输出第二个至第三个的元素print(tuple[2:])  # 输出从第三个开始至列表末尾的所有元素print(tinytuple * 2)  # 输出元组两次print(tuple + tinytuple)  # 打印组合的元组"""输出结果('abcd', 786, 2.23, 'john', 70.2)abcd(786, 2.23)(2.23, 'john', 70.2)(123, 'john', 123, 'john')('abcd', 786, 2.23, 'john', 70.2, 123, 'john')"""# dictionary（字典）dict = {}dict['one'] = "This is one"dict[2] = "This is two"tinydict = {'name': 'john', 'code': 6734, 'dept': 'sales'}print(dict['one'])  # 输出键为'one' 的值print(dict[2])  # 输出键为 2 的值print(tinydict)  # 输出完整的字典print(tinydict.keys())  # 输出所有键print(tinydict.values())  # 输出所有值"""输出结果This is oneThis is two{'code': 6734, 'dept': 'sales', 'name': 'john'}dict_keys(['code', 'dept', 'name'])dict_values([6734, 'sales', 'john'])"""