msg =
(msg[5(msg[len(msg)-1(msg[-1=
<span style="color: #008000">#
<span style="color: #008000"> 2、切片(顾头不顾尾，步长): 想要从一个大字符串中切出一个小字符串
msg=<span style="color: #800000">'<span style="color: #800000">hello world<span style="color: #800000">'
<span style="color: #0000ff">print(msg[0:5<span style="color: #000000">])
<span style="color: #0000ff">print<span style="color: #000000">(msg)
<span style="color: #0000ff">print(msg[0:5:2]) <span style="color: #008000">#<span style="color: #008000">0 2 4
<span style="color: #008000">#
<span style="color: #008000"> 了解
msg = <span style="color: #800000">'<span style="color: #800000">hello world<span style="color: #800000">'
<span style="color: #0000ff">print(msg[-1:-5:1<span style="color: #000000">])
<span style="color: #0000ff">print(msg[-1:-5:-1]) <span style="color: #008000">#<span style="color: #008000">d l r o
<span style="color: #0000ff">print(msg[0:5:1<span style="color: #000000">])
<span style="color: #0000ff">print(msg[-1::-1]) <span style="color: #008000">#<span style="color: #008000">掌握
<span style="color: #008000">#
<span style="color: #008000"> # li[4]='e'<span style="color: #008000">
<span style="color: #008000"> del li[0]<span style="color: #008000">
<span style="color: #008000"> print(li)<span style="color: #008000">
<span style="color: #008000">2、切片(顾头不顾尾，步长)<span style="color: #008000">
<span style="color: #008000"> li=['a','d']<span style="color: #008000">
<span style="color: #008000"> print(li[0:3])
