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原创万能计算器——中缀表达式转换成后缀表达式（C++实现）【可以计算小数和负数】

核心代码与思路：int GetExprValue(vector<string> srcVec) //根据后缀表达式求值{ stack<int> temp; char op = '\0'; int a = 0; int b = 0; for (int i = 0; i < srcVec.size(); i++) { op = srcVec[i][srcVec[i].length() - 1]; if (isdigit(op)) { temp.pus

2022-05-10 21:08:47 1432

原创多线程实现生产者-消费者问题——C++版本

问题描述：1）生产者进程每次生产1个产品（产品数量大于4时停止生产）；2）消费者进程每次消耗2个产品；#include <iostream>#include <thread>#include <mutex>#include <condition_variable>using namespace std;std::mutex mu;std::condition_variable cond;void ProduceThread(int *pr

2022-04-03 13:36:02 1587

原创 Python———删除字符串中的特殊字符

# Demo1: delete the space in src(' www.david@163.com ')# Demo2: delete the '\r' in string from windows file then get linux format without '\r'# Demo3: delete the hanyupinyin tones in 'wén zhāng běn tiān chéng ，miào shǒu ǒu dé zhī 'import unicodedat

2022-01-01 11:53:41 644

原创 Python——字符串的对齐问题

# Now we have a src dict as following:# src_dict = {# 'David':2000# 'Jony':12.3# 'Michel Jackson': 12# 'MM': 13.2# }# we need to get alignment-seted dict as following# dest_dict = {# 'David ':2000# 'Jony ':12.3# 'Michel Jackson'

2021-12-31 23:38:46 730

原创 Python——字符串的连接

# Demo: Now we have a big list with different base data bype(str,int,float)# we need to contact them into a fianl stringsrc = ['abc', 123, 'defg', 49.8, '2021-01-21', '21:23:25']# solution 1:[not recommended as it cost a lot of memory]dest = ''for

2021-12-31 23:18:13 414

原创 Python——将日期格式yyyy-mm-dd转换为mm/dd/yyyy

import relog = open('time.log', 'r').read()print(==========before translating============)print(log)new_log = re.sub('(?P<year>\d{4})-(?P<month>\d{2})-(?P<day>\d{2})', r'\g<month>/\g<day>/\g<year>', log, 10)print(==

2021-12-31 23:04:24 2767

原创 Python——找到特定目录下的特定格式文件并修改权限

#Demo: find files ends with '.py' or '.sh' and change its mode executiveimport os, statfile_list = os.listdir('./files') # find all files in dest dirprint(file_list)dest_files = [x for x in file_list if x.endswith(('.sh', '.py'))]print(dest_files)

2021-12-31 22:41:32 1647

原创 Python——拆分包含多种分隔符的字符串

2021-12-30 23:06:20 249

原创如何学习一门新的编程语言

既然是学习一门新的编程语言，那么前提就是你已经学习过了一门编程语言了——比如C语言（计算机专业出身的应该都学过）；在学习新的编程语言的之前要做的不是网上/书店到处找“快速入门”、“21天掌握”之类的“速成秘籍”，而是将已经学习的语言中的框架结构梳理清楚；这一点非常重要，尤其是在互联网高度发达的今天，搜寻一门语言的入门书籍成了一件非常稀松平常的事情，但是正是因为这样，导致我们在选择书籍的时候眼花缭乱，这样就很难学精，学透；我本人是计算机科班出身，接触的第一门语言就是C语言，当时只是掌握了C语言的大部分语法，

2021-12-29 22:19:31 603

原创 Python——for语句中访问可迭代对象

#coding utf-8from random import randintfrom itertools import chain# Demo1: get the total scores of each student; score stored in 3 lists(math,chinese,english)stu_count = 50math = [randint(60, 100) for x in range(stu_count)]chinese = [randint(60, 1

2021-12-29 21:55:03 297

原创 Python——自定义逆序迭代对象

#coding utf-8precision = 0.00000000001 # ensure no exception occurs of float compare operationclass FloatRange: def __init__(self, start, end, step = 0.1) : self.start = start self.end = end self.step = step def __iter__(self) : temp = self.s

2021-12-29 21:53:56 263

原创 Python——yield关键字的应用

程序功能：获取[start，end)区间的质数；from math import sqrtclass PrimeList: def __init__(self, start, end) : self.start = start self.end = end def is_prime(self, num) : if num < 2 : return False for v in (2, sqrt(num) + 1) : if num % v == 0 : r

2021-12-28 23:21:11 196

原创 Pthon——自定义迭代器和可迭代对象

#coding:utf-8from collections.abc import Iterator, Iterablefrom random import randintdef get_weather(city) : return city + str(randint(20, 35))class WeatherIterator(Iterator): def __init__(self, cities) : self.cities = cities self.index = 0

2021-12-28 22:35:42 328

原创 Python——实现历史记录的功能

游戏描述：猜大小。系统随机生成一个整数（1，100）用户通过输入数据来猜测该整数的值；系统根据输入返回三种结果：too big, too small, you win.输入过程中可以查看最近输入了哪些数字，游戏结束后将历史记录值保存在文件’history’中。from random import randintfrom collections import dequeimport picklehistory = deque([], 6)dest = randint(1, 100)def gu

2021-12-26 22:26:51 3229

原创 Python——保持字典的有序性

from random import randintfrom collections import OrderedDictfrom time import timeordered_dict = OrderedDict()players = list('ABCDEFGHI')start_second = time()for i in range(9) : input() p = players.pop(randint(0, 8-i)) end_second = time() print

2021-12-26 21:43:33 676

原创 Python——求多个字典中的公共键有哪些

# Demo1: get the common key in server sets(transeform from dicts)from random import randint, samplefrom functools import reducel = sample('abcdefgh', randint(3, 6))s1 = {x:randint(1, 5) for x in sample('abcdefgh', randint(3, 6))}s2 = {x:randint(1, 5)

2021-12-26 21:13:27 116

原创 Python——字典元素的排序

# Here is a dict with several members, we need to sort them increasingly# Solution 1print('------------------------solution1----------')from random import randintsrc_dict = {x:randint(60, 100) for x in 'BaCdEfGcMzYW'}print(src_dict)dest_temp = zip(sr

2021-12-26 20:51:15 293

原创 Python——根据序列中的元素出现频率筛选频度较高的元素

# Demo1: generate a list with 100 integers(radom value 1_20)# then get the top 3 frequency numbersfrom random import randintfrom collections import Counterimport resrc = [randint(1, 20) for _ in range(100)]dict_src = dict.fromkeys(src, 0)for x in sr

2021-12-26 19:28:44 315

原创 Python——为元组元素命名

# here is a tuple ('David', 29, 'male', '23raff@163.com'), when we want to get its member# we have to use indexe = ('David', 29, 'male', '23raff@163.com')print(e[0])print(e[1])print(e[2])print(e[3])# it is not abvious when we want to the identity o

2021-12-26 17:22:38 469

原创 Python——列表、字典和集合的解析

# Demo1 screen right data you want to get from list by functiondef screen(data): new_data = [] for i in data : if i>0 : new_data.append(i) return new_datafrom random import randintdata = [randint(-10, 10) for _ in range(10)]print('src list:

2021-12-26 17:04:35 138

原创 Python实现文件读写操作

def my_copy(src_file, dest_file) : try: src_file_obj = open(src_file, 'rb') except FileNotFoundError: print('src file is not found, please check the paragram') return dest_file_obj = open(dest_file, 'wb') for block in src_file_obj : dest_file_o

2021-12-22 22:44:56 224

原创 Python——一个例子感受一下“面向对象”

import scheduleimport timedef job() : print('Hello Python')schedule.every(3).seconds.do(job)while True: schedule.run_pending() time.sleep(1)

2021-12-22 21:15:24 321

原创 Python中的多态实例

class Animal(object): def eat(self) : print('Animal eat something')class Dog(Animal): def eat(self) : print('Dog eats meat')class Cat(Animal): print('Cat eats fish')animal = Animal()dog = Dog()cat = Cat()animal.eat()dog.eat()cat.eat()输出

2021-12-22 21:14:17 610

原创 Python——模块和主函数调用

python_module.py#Demo 1: revoke the default function called pow# print(pow(3, 3))#Demo 2: revoke the function pow in math# from math import pow# print(pow(3, 3))#Demo 3: revoke the self defined function of powimport syssys.path.append('./common')

2021-12-20 22:31:14 1130

原创 Python———init()和new()调用与重写

class MyClass(object): def __new__(cls, *args, **kargs) : print('__new__ method is called and id is {0}'.format(id(cls))) obj = super().__new__(cls) print('id of object is {0}'.format(id(obj))) return obj; def __init__(self, name, age) : super(

2021-12-19 20:35:10 189

原创 Python——多态的实现

class Animal(object): def eat(self) : print('Animal eat something')class Dog(Animal): def eat(self) : print('Dog eats meat')class Cat(Animal): def eat(self) : print('Cat eats fish')animal = Animal()dog = Dog()cat = Cat()animal.eat()dog.eat

2021-12-19 19:22:00 272

原创 Python——继承的实现

# class Person:# def __init__(self, name, age) :# self.name = name# self.age = age# def say_hello(self) :# print('name:', self.name, 'age:', self.age)# mr_smith = Person('Smith', 30)# mr_smith.say_hello()# print(mr_smith)class Person: de

2021-12-19 19:08:25 220

原创 Python——属性和方法的动态绑定

# as the following example, we can create different object with different name or age# but when we want to add a new attribute gender for Smith but not for Jack# Now how we can solve itclass MyClass: def __init__(self, name, age) : self.name = name

2021-12-19 17:17:05 102

原创 Python面向对象——类的封装

# Demo1: put the attribute of a person(Smith, 30years old) into a class name MyClassclass MyClass: name = 'Smith' age = 30 def say_hello(self) : print('My name is %s, and I am %d years old.'%(self.name, self.age))mr_smith = MyClass()mr_smith.say_h

2021-12-19 16:57:53 152

原创 Python——字符串的编码与解码

#encoding and decoding of strsrc = '天生我材必有用's_gbk = src.encode(encoding = 'GBK')s_utf8 = src.encode(encoding = 'UTF-8')print(s_gbk)print(s_utf8)dest_str_from_gbk = s_gbk.decode(encoding = 'GBK')dest_str_from_utf8 = s_utf8.decode(encoding = 'UTF-8')

2021-12-19 16:56:47 288

原创 Python——字符串的格式化输出

# string format output# using %name = '孙悟空'age = 550print('myname is %s and my age is %d'%(name, age))# using .formatprint('myname is {0} and my age is {1}'.format(name, age))#format usage of int and floatnum1 = 200print('%d'%num1)print('%10d'%n

2021-12-19 16:55:56 143

原创 Python——字符串的切片

src = 'hello, python'# how to get 'hello's1 = src[:5]# how to get 'python's2 = src[6:]# how to contact 'hello' and 'python' with '!'s3 = s1 + '!' + s2# show the id of string above allprint(id(src))print(id(s1))print(id(s2))print(id(s3))# how

2021-12-19 16:54:45 218

原创 python学习第二天——装饰器

# decrator of python# definition of func# def func() :# print('Hello world')# def new_func() :# print('decrating new_func')# func()# print('end decrating')# new_func()# when other func needs decrating, we should define another new_func# h

2021-12-14 22:50:11 567

原创计数排序的Python实现

学习Python的第一天，实现计数排序算法；import randomdef list_init(array, size): for i in range(size): array[i] = random.randint(1, size) return arraydef count_sort(array, size): max = array[0] min = array[0] for index in range(size): if max < array[index]:

2021-12-12 17:29:34 632

原创如何理解IT工程师文化

如何理解IT工程师文化？必须首先说清楚IT产业的承载——计算机；从本质上说，计算机是工具——是帮助我们实现算力范围内的和谐地解决实际问题的工具。从这一点出发进行讨论的时候，我们就要考虑我们从事的IT产业最终是服务于“内容”；这里的“内容”可以是多种多样的，从这个意义上来说，当今的所有和IT相关的产业恐怕要占据我们日常生活的90%以上。然而，有一些产业表面上看是IT产业，实际上它们的核心则是工业产品；比如：工业软件、管理软件等。尽管IT主导的信息产业革命被很多人称作是“人类第四次革命”；然而今天IT产业本身

2021-12-11 20:43:34 528

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