统计一个字符串中每个字符出现的次数和井字棋盘游戏

练习有一个小程序，计算一个字符串中每个字符出现的次数。

代码如下：

#统计一个字符串中每个字符出现的次数
messages = 'It was a bright cold day in Feb 23,and the clocks were striking twelve'
count = {}
for i in messages:
    count.setdefault(i,0)
    count[i] = count[i] + 1
print(count)

执行结果如下：

井字棋盘数据结构建模例子：
代码如下：

#井字棋盘,数据结构建模
chessboard = {'t-l':' ','t-c':' ','t-r':' ',
              'c-l':' ','c-c':' ','c-r':' ',
              'b-l':' ','b-c':' ','b-r':' '
              }
def printboadr(board):
    print(board['t-l']+'|'+board['t-c']+'|'+board['t-r'])
    print('-*-*-')
    print(board['c-l']+'|'+board['c-c']+'|'+board['c-r'])
    print('-*-*-')
    print(board['b-l']+'|'+board['b-c']+'|'+board['b-r'])
turn = 'X'
for i in range(9):
    printboadr(chessboard)
    print('please choose a place to fill it(for example:t-l)')
    play = input()
    chessboard[play] = turn
    if turn == 'X':
        turn = 'O'
    else:
        turn ='X'
printboadr(chessboard)

执行结果如下：

后边还会有各种小练习和项目练习。