python核心编程第二章习题

"""
python核心编程练习2
使用的python版本: Python 3.2.3
"""

def t2_5():
    """分别写一个while和for循环，输出整数0～10。
    """
    i = 0
    while i <= 10:
        print(i,'', end='')
        i += 1
    print()

    for i in range(0, 11):
        print(i,'', end='')
    print()

def t2_6():
    """条件判断。

        判断一个数是整数，负数，或者等于0.
    """
    try:
        anum = int(input('Enter a number: '))
    except ValueError:
        print('what you entered is not a number!!!')
    else:
        print(anum)

def t2_7():
    """输入一个字符串，逐个字符输出该字符串。使用while和for
    """
    astr = input('Enter a string: ')
    for eachar in astr:        print(eachar, end='')
    print()

    strlen = len(astr)
    i = 0
    while i < strlen:
        print(astr[i], end='')
        i += 1
    print()

def t2_8():
    """输入5个数，分别存入list和tuple，算出他们的和
    """
    alist = []
    atuple = ()
    for i in range(0, 5):
        num = int(input('Enter a number: '))
        alist.append(num)
        atuple = atuple + (num, )
    
    total = 0
    for num in alist:
        total += num
    print(total)

    total = 0
    for num in atuple:
        total += int(num)
    print(total)

def t2_9():
    """输入5个数，存入list和tuple，算出他们的平均值

        在python3.2版本中，单除号/实现的是小数除法，可以直接用，不过这里考虑
        输入的数可能为浮点数，所以也用float对输入进行转换
        如果在2.x版本中，如果输入的是整数，需要先将数转成float，再除
    """
    alist = []
    atuple = ()

    # input 5 numbers
    for i in range(0, 5):
        num = float(input('Enter a number: '))
        alist.append(num)
        atuple = atuple + (num, ) # 向一个tuple添加元素，要使用tuple相加
                                  # 所以这里先办单个数num组成一个只有一个
                                  # 元素的tuple再与原来的tuple相加
    total = 0
    for num in alist:
       total += num
    print(total/len(alist))

    total = 0
    for num in atuple:
        total += num
    print(total/len(atuple))

def t2_10():
    """让用户输入一个1～100之间的数，如果用户输入的数满足条件，
    显示成功并推出，否则显示错误信息，然后再次提示用户输入。
    """
    prompt = 'Please input a number (1~100): '
    while True:
        try:
            num = int(input(prompt))
        except ValueError:
            print('Not a number')
        else:
            if 1 <= num <= 100:
                break
            else:
                print(num, 'not correct')
    print('Yes, you got it.')

def t2_11():
    """带文本菜单的程序。

        菜单如下(1)取5个数的和 （2）取5个数的平均值 （X）退出
    """
    prompts = '''
(1)sum of five numbers.
(2)average of five numbers.
(X)Quit
Enter your choice: '''

    while True:
        choice = input(prompts).strip()[0].lower()
        print('\nYou picked [{}]'.format(choice))

        if choice not in '12x':
            print('Invalid options:', choice)
        elif choice == '1':
            t2_8()
        elif choice == '2':
            t2_9()
        else:
            break

def t2_15():
    """用户输入三个数，保存至不同的变量中。不使用列表或排序算法，
    自己写代码来对这三个数进行排序：从大到小，从小到大
    """
    aa = int(input('Enter a number: '))
    bb = int(input('Enter a number: '))
    cc = int(input('Enter a number: '))
   
    a, b, c = aa, bb, cc
    # from smallest to largest
    if a > b:
        a, b = b, a # swap two value
    if a > c:
        a, c = c, a
    if b > c:
        b, c = c, b
    print('{} < {} < {}'.format(a, b, c))

    # from largest to smallest
    a, b, c = aa, bb, cc
    if a < b:
        a, b = b, a
    if a < c:
        a, c = c, a
    if b < c:
        b, c = c, b
    print('{} > {} > {}'.format(a, b, c))

def t2_16():
    """输入一个文件名，然后读取该文件，并将文件内容输入到屏幕上
    """
    filename = input('Enter file name: ')
    fobj = open(filename, 'r')
    for eachline in fobj:
        print(eachline, end='') # 默认的print语句会加换行，这里把换行去掉
    fobj.close()
    

if __name__ == '__main__':
    #t2_5()
    #t2_6()
    #t2_7()
    #t2_8()
    #t2_9()
    #t2_10()
    #t2_11()
    #t2_15()
    #t2_16()