def reverse_find_substring(str, sub): """ 在一个字符串中反向查找子串 :param str: 源字符串 :param sub: 需查找的子串 :return: 如找到，返加子串的位置，否则返回-1 """ if sub not in str: # 如果子串不在源字符串中，则返回-1 return -1 else: # 如果子串在源字符串中，则反向查找子串 str_len = len(str) sub_len = len(sub) for i in range(str_len - sub_len, -1, -1): if str[i:i+sub_len] == sub: return i return -1 # 如果未找到子串，则返回-1

测试

print(reverse_find_substring('hello world', 'world')) # 6 print(reverse_find_substring('hello world', 'python')) # -1 print(reverse_find_substring('python is a programming language', 'is')) # 7 print(reverse_find_substring('python is a programming language', 'language')) # 22 print(reverse_find_substring('python is a programming language', 'python')) #