python3默認字符集默認是Unicode
python2默認字符集默認是ASCII

print(‘hello_world!‘)

name = ‘小老虎‘
age = 27

print("let‘s go!")
print(‘你真"帥啊"‘)
print(‘‘‘let‘s go "帥"‘‘‘)

‘‘‘
這是一段多行註釋
用三引號就可以了
‘‘‘

需要註意python中不能使用關鍵字做變量名

name1 = input(‘請輸入你的名字：‘)
print(‘你的名字是：‘, name1)

分支語句 if elif else

# username = input(‘請輸入您的用戶名：‘)
# password = input(‘請輸入您的密碼：‘)
# if username == ‘wangsilei‘ and password == 123456:
#     print(‘歡迎光臨！‘)
# else:
#     print(‘賬號/密碼錯誤！‘)

# input接受到的都是str類型的
# score = input(‘請輸入你的分數：‘)
# if int(score) < 60:
#     if int(score) >= 50:
#         print(‘50-60‘)
#     else:
#         print(‘太低了！‘)
#     print(‘不及格！‘)
# elif 60 <= int(score) < 80:
#     print(‘及格！‘)
# elif 80 <= int(score) < 90:
#     print(‘良好!‘)
# else:
#     print(‘優秀！‘)

# == != < > <= >=比較運算符

sex = input(‘請輸入你的性別：‘)
if sex == ‘男‘ or sex == ‘女‘:
    print(‘性別輸入正確！‘)
else:
    print(‘性別輸入有誤!‘)

# 布爾類型 True False

for、while循環
 

import random


# 循環 叠代 遍歷
# for while

# break結束循環
# continue結束本次循環，繼續下一次循環
# count = 0
# while count < 10:
#     print(‘哈哈哈哈‘)
#     count += 1
#     print(‘666‘)
#     break
# else:  # 循環正常結束運行它
#     print(‘done!‘)

# count = 0
# while count < 3:
#     username = input(‘請輸入名字：‘)
#     password = input(‘請輸入密碼：‘)
#     if username == ‘wangsilei‘ and password == ‘123456‘:
#         print(‘登錄成功！‘)
#         break
#     else:
#         print(‘名字/密碼錯誤！‘)
#     count += 1
# else:
#     print(‘錯誤次數過多!‘)
# for i in range(10):
#     print(i)
random_number = random.randint(1, 1000)
for i in range(3):
    number = int(input(‘請輸入你猜的數字:‘))
    if number > random_number:
        print(‘你猜的太大了!‘)
    elif number < random_number:
        print(‘你猜的太小了!‘)
    else:
        print(‘你猜對了，答案是：‘, random_number)
        break

猜數字遊戲
 

import random


# 以下代碼不加continue也可以
random_number = random.randint(1, 1000)
count = 0
while count < 7:
    count += 1
    number = int(input(‘請輸入你猜的數字:‘))
    if number > random_number:
        print(‘你猜的太大了!‘)
        continue
    elif number < random_number:
        print(‘你猜的太小了!‘)
        continue
    else:
        print(‘你猜對了，答案是：‘, random_number)
        break

字符串格式化
 

username = input(‘請輸入你的名字：‘)
time = ‘2017-12-17 17:19:00‘
print(‘歡迎光臨‘ + username)  # 通過+號拼接兩個字符串
print(‘歡迎光臨%s,時間是%s‘ % (username, time))  # 這種方式效率高
print(‘歡迎光臨{},時間是{}‘.format(username, time))  # 這種比第二種好
print(‘歡迎光臨{name},時間是{date}‘.format(name=username, date=time))

# %s後跟字符串 %d後跟整數 %f小數類型

number = 123
print(‘%.2f‘ % number)  # 保留兩位小數

登錄小程序

username = ‘wangsilei‘
password = 123456

for i in range(3):
    name = input(‘請輸入賬戶名稱：‘)
    pwd = input(‘請輸入賬戶密碼：‘)
    if name == username and int(pwd) == password:
        print(‘{}歡迎登錄‘.format(name))
        break
    elif name == ‘‘ or pwd == ‘‘:
        print(‘賬戶名稱/賬戶密碼不可為空‘)
    elif name.isspace() or pwd.isspace():
        print(‘賬戶名稱/賬戶密碼不可為空格‘)
    else:
        print(‘賬戶名稱/密碼錯誤！‘)

生成手機號碼並寫入txt小程序

import random


phone_lists = [‘130‘, ‘131‘, ‘132‘, ‘133‘, ‘134‘, ‘135‘, ‘136‘, ‘170‘, ‘180‘]
phone_str = ‘0123456789‘

n = int(input(‘生成多少個隨機的電話號碼：‘))
with open(r‘C:\Users\wangsilei\Desktop\phone.txt‘, ‘w‘) as f:
    for i in range(n):
        phone_numbers = random.choice(phone_lists) + ‘‘.join(random.choice(phone_str) for j in range(8)) + ‘\n‘
        f.write(phone_numbers)

python之helloworld