二、python基本语法(python3.6)

• 学习前仪式
  print("hello word!")
  ps: 熟练各种语言的hello world书写, 嘻嘻
• 注释
  单行注视：# 被注释内容
  多行注释：""" 被注释内容 """ 或者 '''被注释内容'''
• 变量
  变量定义的规则：
  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
  以下关键字不能声明为变量名
  ['and', 'as', 'assert', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'exec', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'not', 'or', 'pass', 'print', 'raise', 'return', 'try', 'while', 'with', 'yield']

代码

# Author:Scott She
name = "Scott She"
name2 = name
print("My name is ", name, ", again, my name is ", name2)
name = "马云"
print(name, name2)
# 单引号和双引号基本一样, 三个单(或双)引号还能打印多行, 也可以注释多行 
lines = """
name = "马云"
print(name, name2)
"""
print(lines)

打印

• 用户输入及字符串格式化

代码

# Author:Scott She
name = input("name ")
age = int(input("age "))
job = input("job ")
salary = float(input("salary "))
print(type(name), type(age), type(job), type(salary))
info1 = """ 
---------------- info of %s ------------------
Name: %s
Age: %d
Job: %s
Salary: %.1f
""" % (name, name, age, job, salary)
print(info1)
info2 = '''
---------------- info of {_name} ------------------
Name: {_name}
Age: {_age}
Job: {_job}
Salary: {_salary}
'''.format(_name=name,
           _age=age,
           _job=job,
           _salary=salary)
print(info2)
info3 = '''
---------------- info of {0} ------------------
Name: {0}
Age: {1}
Job: {2}
Salary: {3}
'''.format(name,
           age,
           job,
           salary)
print(info3)
# 以上三种字符串格式化, 一般都会用第二种

打印

• if 语句及密文

代码

# Author:Scott She
import getpass    # 模块
_username = "scott"
_password = "666666"
username = input("username ")
password = getpass.getpass("password ")   # 注意, 该方法在PyCharm中不能运行,可以用终端测试
if _username == username and _password == password:
    print("Wellcom {name} login...".format(name=username))
else:
    print("Invalid username or password!")

终端测试

• 循环语句

# Author:Scott She
age_of_scott = 25
# while循环
'''
count = 0
while count < 3:
    guess_age = int(input("age "))
    if guess_age == age_of_scott:
        print("yes, you got it")
        break
    elif guess_age > age_of_scott:
        print("think smaller...")
    else:
        print("think bigger...")
    count += 1
else:
    print("you have tried too many... fuck off")
'''
# for循环
'''
for i in range(3):
    guess_age = int(input("age "))
    if guess_age == age_of_scott:
        print("yes, you got it")
        break
    elif guess_age > age_of_scott:
        print("think smaller...")
    else:
        print("think bigger...")
else:
    print("you have tried too many... fuck off")
'''
# for循环详解
''' 
类似于其他语言中的 
for (int i = 0; i < 10; i+=2) {
    print(i)
}
'''
for i in range(0, 10, 2):
    print(i)
count = 0
while count < 3:
    guess_age = int(input("age "))
    if guess_age == age_of_scott:
        print("yes, you got it")
        break
    elif guess_age > age_of_scott:
        print("think smaller...")
    else:
        print("think bigger...")
    count += 1
    if count == 3:
        print("Do you want to keep guessing... n or N for no, others for yes: ")
        continue_confirm = input()
        if continue_confirm != "n" and continue_confirm != "N":
            count = 0

打印

• 三元运算
  result = 值1 if 条件 else 值2
  如果条件为真：result = 值1
  如果条件为假：result = 值2

由于简书格式原因, 代码均没有空行, 可以去这里下载我的练习代码