[2.1] Python study notes Day03 variables and strings

1. Variables

Variable var, try to choose a professional name named

Variable usage rules:

# Before use variables must be assigned
# variables need not be declared, it can be assigned directly
# variable name can contain letters, numbers, underscores, but can not begin with a numeric
# uppercase and lowercase letters are different variable name
the # symbol is assigned =

teacher = "weivid"
print(teacher)

teacher = "weivid1"
print(teacher)

first = 3
second = 8
third = first + second
print(third)

operation result:

2. String

2.1 string concatenation

# Also known as text strings, different from the numbers, two are completely different

String String is spliced ​​+

myteacher = "weivid"
yourteacher = "wang"
ourteacher = myteacher + yourteacher
print(ourteacher)

operation result:

2.2 Creating strings

Need quotes around character, may be a single or double quotation marks, must be paired
specific characters need to use the escape character \

print('5'+'8') 		#两个字符的拼接
print('Let\'s go')
print("Let's go")	#可以使用双引号里加单引号的形式正常打印

operation result:

2.3 the original string

2.3.1 use the escape character \ escapes

2.3.2 escape r (original string raw) before the string

End of the original string can not add a backslash \

print('C:\now') 
print('C:\\now')#使用反斜杠\进行转义
print('C:\\now\\uesr\\weivid\\home\\Desktop')
print(r'C:\now\uesr\weivid\home\Desktop')#对于字符串中有很多反斜杠\，可以使用在字符串r进行转义
#print(r'C:\now\uesr\weivid\home\Desktop\')error

operation result:

2.3.3 backslash end of the method

print(r'C:\now\uesr\weivid\home\Desktop\\'[:-1])
print(r'C:\now\uesr\weivid\home\Desktop' + '\\' )
print(r'C:\now\uesr\weivid\home\Desktop\ ')

operation result:

2.3.4 long string

Triple quotes "" "" "" ", '' '' ''
# long string across multiple lines
following the mini-game is to modify the code after printing

print(
"""
print("第二课\n小的游戏规则")

print("--------我是weivid_wang----------")
temp = input("猜一下weivid_wang心中想的是哪个数：")
guess = int(temp)
if guess < 8:
    print ("shu")
if guess == 8:
    print("卧槽你是我心中的蛔虫吗\n哼猜中了也没有奖励！！")
else:
    print("猜错了，我心中的想的是8！！")
print("游戏结束，不玩啦！")
"""
)

operation result: