python反轉字符串的幾種方式

class StringReverse(object):
    # 1.切片操作
    def string_reverse_1(self, s):
        return s[::-1]


    # 2.轉換成list,再reverse，之後重組字符串
    def string_reverse_2(self, s):
        s_list = list(s)
        s_list.reverse()
        return "".join(s_list)


    # 3.將字符串轉換成列表後，交換前後兩個字符串的位置，再重組字符串
    def string_reverse_3(self, s):
        s_list = list(s)
        index_begin = 0
        index_end = len(s_list)-1
        while index_begin < index_end:
            s_list[index_begin],s_list[index_end] = s_list[index_end],s_list[index_begin]
            index_begin += 1
            index_end -= 1
        return "".join(s_list)

    # 4.利用collections中的雙向列表deque,而且deque是線程安全的，可以同時從deque的左右兩端提取元素
    def string_reverse_4(self, s):
        from collections import deque
        d = deque()
        # 從左邊添加元素
        d.extendleft(s)
        return "".join(d)
        d.appendleft("h")
        # 從右邊添加元素
        d.extend(s)
        d.append("i")
        right = d.pop()
        left = d.popleft()

    # 5.利用遞歸
    def string_reverse_5(self, s):
        if len(s) <= 1:
            return s
        return self.string_reverse_5(s[1:]) + s[0]

    # 6.循環字符串元素
    def string_reverse_6(self, s):
        return "".join([s[i] for i in range(len(s)-1,-1,-1)])

if __name__ == "__main__":
    stringReverse = StringReverse()
    s = "abcdefg"
    print "string_reverse_1", stringReverse.string_reverse_1(s)
    print "string_reverse_2", stringReverse.string_reverse_2(s)
    print "string_reverse_3", stringReverse.string_reverse_3(s)
    print "string_reverse_4", stringReverse.string_reverse_4(s)
    print "string_reverse_5", stringReverse.string_reverse_5(s)
    print "string_reverse_6", stringReverse.string_reverse_6(s)

輸出結果爲：

string_reverse_1 gfedcba
string_reverse_2 gfedcba
string_reverse_3 gfedcba
string_reverse_4 gfedcba
string_reverse_5 gfedcba
string_reverse_6 gfedcba