2019-11-11Day6 Homework

# 1.查询某个元素出现次数
names = [3, 3, 3, 4, 4, 7, 3, 2, 3, 4]
times = 0  # 寻找到的数的次数
n = 3  # 需要寻找的数
for index in range(len(names)):
    print(index)
    if names[index] == n:
        times += 1
print(n, "出现的次数是：", times)

# 2.在列表末尾追加多个值
names = [3, 3, 3, 4, 4, 7, 3, 2, 3, 4]
add = [1, 2, 3]
for i in range(len(add)):
    x = add[i]
    names.append(x)
print(names)

# 3.index 找出某个值第一个匹配对象的位置
add = [1, 2, 3]
value = int(input("某个值："))
for i in range(len(add)):
    if add[i] == value:
        print(i, "位置找到该值！")
        break

# 4.反向列表中的所有元素
reverse = [0, 1, 2, 3, 4, 5,6]
# if len(reverse) & 1 == 1:  # 如果是奇数的话 中间不变 左右互换
for i in range(int(len(reverse) / 2)):
    reverse[i], reverse[-(i + 1)] = reverse[-(i + 1)], reverse[i]
# else:


print(reverse)