python 练习

friends = []
def add_friend():
    name = raw_input("please input friend name:")
    friends.append(name)
    foreach(friends)
def del_friend():
    name = raw_input("please input friend name who you want to delete:")
    if friends.index(name)!=-1:
        friends.remove(name)
    foreach(friends)
def update_friend():
    name = raw_input("please input friend name who you want to update:")
    index = friends.index(name)
    name = raw_input("please input friend name new")
    if index != -1:
        friends[index] = name
    foreach(friends)
def query_friend():
    name = raw_input("please input friend name to query:")
    print(name)

whencase={
    1:lambda _:add_friend(),
    2:lambda _:del_friend(),
    3:lambda _:update_friend(),
    4:lambda _:query_friend()
}
while True:
    print("-"*40)
    print("  1  :  添加用户名")
    print("  2  :  删除用户名")
    print("  3  :  修改用户名")
    print("  4  :  查询用户名")
    print("  5  :  退出系统")
    print("-"*40)
    #提示用户输入
    numstr = raw_input("请输入功能序号")
    if not numstr.isdigit():
        break
    numstr = int(numstr)
    if numstr == 5:
        break
    elif numstr<5:
        whencase[numstr]
    else:
        continue