python第一课

print("Hello World!")

直接打印:Hello World!

可以直接用text文本写程序，完成之后，将后缀修改为 .py

# 是用来注释单行，注释多行使用 ''' ''',或者""" """

#！/usr/bin/env python   env找环境变量

各种语言的Hello word！

C++ 语言

#include<iostream>

int main(void)

{

std::cout<<"Hello world!";

}

C语言

#include<stdio.h>

int main(void)

{

printf("\nhello world!");

return 0;

}

java 语言

public class HelloWorld{

//程序的入口

 public static void main(String args[]){

 //向控制台输出信息

 System.out.println("Hello World!");

 }

}

PHP语言

<?php

   echo "Hello World!";

?>

RUBY 语言

puts "Hello world!"

Go语言

package main

import "fmt"

func main(){

  fmt.Printf("Hello World!\n God Bless You!");

}

课程主要使用pycharm

file--new project--location写名称--interpreter选择执行版本

创建目录 new directory

创建文件 python file--起名字

editor -- file and code templates 选择一个模板或新建模板

变量

name = "Alex Li"  # name就是变量

name2 = name

print("My name is ", name, name2)

name = "PaoChe Ge"

gf_of_oldboy  = "Chen rong hua"

#大写的变量名一般作为不可变的量赋值使用

print(name, name2)

变量名只能是字母，数字或下划线的任意组合

变量名的第一个字符不能是数字

关键字不要声明为变量如['and','if'……]

起变量名的时候请注意使用类似功能的英文单词

字符编码

ASCII码 最多用8位来表示，最多存255个

GB2312 存了7445个字符，1995年gbk收录了21886个字符，2000年GB18030收录了27484个字符

Unicode(统一码、万国码、单一码)

ASCII占8位1个字节，Unicode占16位2个字节

utf-8可变长度，utf-8存英文用1字节，存中文3字节

ASCII 255 1bytes

  --> 1980 gb2312 7xxxx

   -->1995 GBK1.0 2W+

    -->2000 GB18030 27xxx

   -->unicode 2bytes

      -->utf-8  en:1bytes,zh:3bytes

py2 写入中文，需要加 # -*- coding:utf-8 -*-

py3 默认utf-8

用户输入

name = input("name:")

age= input("age:")

job= input("job:")

salary= input("salary:")

password = input("password:")

print(username,password)

info = '''

--------info of %s--------

Name:%s

Age:%s 

Job:%s

Salary:%s

''' %(name, name,age,job,salary)

info2 = '''

--------info of {_name}--------

Name:_{name}

Age:{_age}

Job:{_job}

Salary:{_salary}

''' .format(_name=name,

_age=age,

_job=job,

_salary=salary)

info3 = '''

--------info of {0}--------

Name:{0}

Age:{1}

Job:{2}

Salary:{3}

''' .format(name,age,job,salary)

print(info3)

print(info2)

print(info)

%s  s=string，%d 只能是数字 %f 浮点型，带小数点

age = int(input("age:"))  强制转换s为整型。input默认为s类型

import getpass  #导入密文密码模块

_username = 'alex'

_password = 'abc123'

username = input("username:")

#password = getpass.getpass("password:") #pycharm 运行好像有问题

password = input("password:")

if _username == username and _password == password:

  print("Welcome user {name} login...".format(name=username))

else:

  print("invalid username or password!")

IndentationError（缩进错误）

新的程序 guess

age_of_oldboy = 56

guess_age = int(input("guess age:"))

if guess_age == age_of_oldboy:

  print("yes, you got it.")

elif guess_age > age_of_oldboy:

  print("think smaller...")

else:

  print("think bigger!")

while循环

count = 0

while True:

   print("count:", count)

  count = count +1 #count+=1

  if count == 1000:

     break

改良的guess

age_of_oldboy = 56
guess_age = int(input("guess age:"))
count = 0
while count < 3:
    if guess_age == age_of_oldboy:
        print("yes, you got it.")
        break
    elif guess_age > age_of_oldboy:
        print("think smaller...")
    else:
        print("think bigger!")
    count += 1
else:
    print("you have tried too many times..fuck off")

for 循环

for i in range(10):
    print("loop", i)

for i in range(0, 10, 2):  #2是步长，默认为1
    print("loop", i)

for i in range(0, 10):
    if i < 3:
        print("loop", i)
    else:
        continue  # 跳出本次循环进入下一次循环
    print("hehe...")

for i in range(10):
    print('------------', i)
    for j in range(10):
        print(j)
        if j > 5:
            break  # 跳出本次循环

guess 改良

age_of_oldboy = 56
guess_age = int(input("guess age:"))
for i in range(3):
    if guess_age == age_of_oldboy:
        print("yes, you got it.")
        break
    elif guess_age > age_of_oldboy:
        print("think smaller...")
    else:
        print("think bigger!")
else:
    print("you have tried too many times..fuck off")

guess 改良

age_of_oldboy = 56
guess_age = int(input("guess age:"))
count = 0
while count < 3:
    if guess_age == age_of_oldboy:
        print("yes, you got it.")
        break
    elif guess_age > age_of_oldboy:
        print("think smaller...")
    else:
        print("think bigger!")
    count += 1
    if count == 3:
        countine_confirm = input("do you want to keep guessing..？")
        if countine_confirm != 'n':
            count = 0
else:
    print("you have tried too many times..fuck off")