字符串知识 ---index ---切片 ---步长

# 字符串
                                                       # "  "   ''   借助函数  。 .format()   %。.........
s1 = "nihao" #   索引--index   []
print(s1[0])
print(s1[1])
print(s1[2])
print(s1[3])
print(s1[4])
# n
# i
# h
# a
# o
#  s1[index]-----索引   0,1,2,3.......
s1 = "nihao"
i = 0
while i <= 4:
    print(s1[i])
    i+=1
# n
# i
# h
# a
# o
# n
s1 = "nihao"
for i in s1:
    print(i)
# n
# i
# h
# a
# o

    #    切片 取内容
s2 = "nihao"
print(s2[1:])
# ihao
print(s2[:2])
# ni
print(s2[0:2])
# ni
print(s2 [1:2])
# i
print(s2[2:5])
# hao

    # 步长   0,1,2......
s3 = "nihaome"
print(s3[1::3])
# io
print(s3[::3])
# nae
print(s3[::2])
# nhoe
print(s3[::])
# nihaome
print(s3[::-1])  #  -1 倒叙取
# emoahin
print(s3[-2:-6:-1])
# moah
print(s3[2:-1])
# haom
print(s3[::-2])
# eohn

#   练习应用  
s4 = "yukebanwozi"
for l in s4:
    print(l)
l1 = "suiiabn"
o = 0
while o <=6:
    print(l1[o])
    o+=1
i1 = "suibian"
print(i1[:6])
# print()
i2 = "nihaomewk"
print(i2[2::5])