#单引号与双引号
print( 'hell "python"' ) #hell "python"
print( "hell 'python'" ) #hell 'python'
print( "hell \"python\"" ) #hell "python"
print( 'hell \'python\'' ) #hell 'python'

#三引号 空行也会输出
print('''
hello
ok
''')
print("====")
print("""
hello
ok
""")

#字符串中使用变量
x=123
print("x=", x) #x= 123
print(f"x={x}") #x=123 嵌入值
print(f"{x} {x} twice") #123 123 twice
y=456
print(f"{x} {y} two numbers") #123 456 two numbers


#字符基本操作
print("x" in "x123") #True
print("x" not in "x123") #False

print("abc"+"def") #abcdef
print("abc"*3) #abcabcabc

#切片
print("abcdef"[3])  #d
print("abcdef"[-1]) #f
print("abcdef"[1:4]) #bc
print("abcdef"[1:]) #bcdef
print("abcdef"[1:5:2]) #bd 从1到5，步长为2