string_reverse

 

if __name__ == '__main__':
    my_string = "Hello, world!"
    print(my_string[::-1])  # !dlrow ,olleH
    print(my_string[::-2])  # !lo olH

    print(my_string[:0:-1])     # !dlrow ,olle
    print(my_string[-2:2:-1])   # dlrow ,ol
    
'''    
    [-2:2:-1]
    -2  开始位置
    2   结束位置:
    -   倒序 
    1 间隔
''' 

 

 

 

def string_reverse():
    s = "abcdrfg"
    for i in range(len(s) - 1, -1, -1):
        print(s[i], end="")

gfrdcba

 

 

def string_reverse():
    s = "abcdrfg"
    print(s[::-1])

gfrdcba

 

 

def string_reverse():
    s = "abcdrfg"
    for char in reversed(s):
        print(char, end="")

gfrdcba

 

def string_reverse():
    s = "abcdrfg"
    print("".join(reversed(s)))

gfrdcba

 

 

def string_reverse():
    s = "abcdrfg"
    i = len(s)
    while i > 0:
        i -= 1
        print(s[i], end="")

gfrdcba

 

def traverse_string_backwards(s):
    print("s:", s)
    if len(s) == 0:
        return
    
    traverse_string_backwards(s[1:])
    print("s:", s, "s[0]:", s[0])

'''
s: abcdrfg
s: bcdrfg
s: cdrfg
s: drfg
s: rfg
s: fg
s: g
s: 
s: g s[0]: g
s: fg s[0]: f
s: rfg s[0]: r
s: drfg s[0]: d
s: cdrfg s[0]: c
s: bcdrfg s[0]: b
s: abcdrfg s[0]: a
'''