Python daily practice (new question bank on Niuke) -- day 2: output string in reverse order

<font color=black size=5> Preface </font>
<font color=black size=3> Recently, many kids who have learned the basics asked me how to improve my programming level ？ What should I do after learning the basics ？ Mingming learned a lot , Do the project but don't know how to get started , In fact, this is too little practice , Only pay attention to learning , But ignore the question , Only continuous practice can improve and consolidate programming thinking and ability ！</br></br></br> I happened to see that niuke.com has recently released Python So I had a good experience with my new question bank </br></br> Link address ： Cattle from  | Python From introduction to practice , Stop talking nonsense and speed up , Or follow the questions below ！！！

1.  Problem description

<font color=green size=4> Enter a string and output it in reverse order </font>

• <font color=black size=4> The first way ： String slice

• <font color=black size=4> The second way ： Use circular conversion and output in reverse order

• <font color=black size=4> such as ： Input string 'hello', Reverse output 'olleh'</br></br>

• <font color=#0099ff size=4> After the partners read the problem description , Be sure to practice yourself first , Then go to see the blogger's code and problem-solving ideas , In order to improve their programming level , It all depends on self-consciousness ！！！

2.  Algorithm ideas

<font color=black size=4>1. Use a loop to subtract the length of the string from the beginning to 0 end <br /><font color=black size=4>2. Every time the circulation inside the body , Add the characters of the corresponding index to the list <br /><font color=black size=4>3. After completing all the cycles , Convert the list to string output

3.  Code implementation

The first way to slice

Implementation code ：
# Python3 range()  It returns an iteratable object （ Type is object ）, Not the list type
# range(start, stop[, step])
#  Parameter description ：
# start： Count from start  Start . The default is 0 Start . for example range (5)  Equivalent to range (0,5) ;
# stop： Count to stop end , But does not include stop.  for example : range (0,5)  yes  [0, 1, 2, 3, 4] No, 5
# step： step , The default is 1. for example : range (0, 5)  Equivalent to  range(0, 5, 1)
# range(5, 0, -1): [5, 4, 3, 2, 1]

#  The first way to slice
str_info = input(" Please enter the string ：")
print(" The output result in reverse order is ：", str_info[::-1])

Running results ：

Second cycle conversion

Implementation code ：
# Python3 range()  It returns an iteratable object （ Type is object ）, Not the list type
# range(start, stop[, step])
#  Parameter description ：
# start： Count from start  Start . The default is 0 Start . for example range (5)  Equivalent to range (0,5) ;
# stop： Count to stop end , But does not include stop.  for example : range (0,5)  yes  [0, 1, 2, 3, 4] No, 5
# step： step , The default is 1. for example : range (0, 5)  Equivalent to  range(0, 5, 1)
# range(5, 0, -1): [5, 4, 3, 2, 1]

#  Second cycle conversion
str_info = input(" Please enter the string ：")
str_list = []
for i in range(len(str_info) - 1, -1, -1):
 str_list.append(str_info[i])

print("str_list：", str_list)
print(" The output result in reverse order is ：", ''.join(str_list))

Code parsing ：

• range(len(str_info) - 1, -1, -1) ： Get string index subscript

• len(str_info) - 1： The maximum index position of the string , Such as hello That is to take 4

• The first 1 individual -1： Because the left is closed and the right is open , Actual value to 0

• The first 2 individual -1： flashback

• ''.join(str_list)： List strings ['o', 'l', 'l', 'e', 'h'] Convert to olleh character string

Running results ：