一文带你掌握Python内置reversed函数的使用

reversed(seq)

# 定义一个字符串
my_string = "Hello, Python!"
 
# 使用reversed函数反转字符串
reversed_string = ''.join(reversed(my_string))
 
# 输出反转后的字符串
print(reversed_string)

# 定义一个列表
my_list = [1, 2, 3, 4, 5]
 
# 使用reversed函数反转列表
reversed_list = list(reversed(my_list))
 
# 输出反转后的列表
print(reversed_list)

my_list = [1, 2, 3, 4, 5]
for item in reversed(my_list):
    print(item)

my_list = [5, 3, 1, 4, 2]
sorted_list = sorted(my_list, reverse=True)
print(sorted_list)

my_list = [1, 2, 3, 4, 5]
value_to_find = 3
if value_to_find in reversed(my_list):
    print(f"{value_to_find} found in the reversed list.")

def is_reverse_string(str1, str2):
    return str1 == ''.join(reversed(str2))
 
string1 = "hello"
string2 = "olleh"
if is_reverse_string(string1, string2):
    print("String2 is the reverse of String1.")

file_path = "sample.txt"
 
# 使用with语句打开文件，确保在退出时自动关闭文件
with open(file_path, "r") as file:
    # 使用reversed函数逆序遍历文件的每一行
    for line in reversed(list(file)):
        print(line.strip())  # 去除每行末尾的换行符

def is_palindrome(word):
    return word == ''.join(reversed(word))
 
word1 = "racecar"
word2 = "hello"
if is_palindrome(word1):
    print(f"{word1} is a palindrome.")
if is_palindrome(word2):
    print(f"{word2} is a palindrome.")

my_string = "Python"
reversed_chars = ''.join(reversed(my_string))
print(reversed_chars)  # 输出：nohtyP

my_list = [1, 2, 3, 4, 5]
for index, value in enumerate(reversed(my_list)):
    my_list[index] = value * 2
 
print(my_list)  # 输出：[10, 8, 6, 4, 2]

my_dict = {'apple': 3, 'banana': 2, 'cherry': 5}
for key in reversed(my_dict):
    print(key, my_dict[key])

my_list = [10, 15, 20, 25, 30]
filtered_list = list(filter(lambda x: x % 2 == 0, reversed(my_list)))
print(filtered_list)  # 输出：[30, 20, 10]