Question

我正在编写一个程序来加载文件中的数据列表，我需要程序来区分行中的数据是字符串还是整数。但是在我完成的代码中，程序并没有区分数字和字符串。

我拥有的数据列表示例：

HAJOS
ALFRED
1896
1

我的代码：

def medalsYear():
  times = 1
  totalGold = 0
  totalSilver = 0
  totalBronze = 0
  while times <= 5:
    alpha = fob.readline() #reads file line by line#
    print(alpha)
    times = times + 1
    if type(alpha) == int:
        if alpha == 1:
            totalGold = totalGold + 1
            print("gold medal won")
        elif alpha == 2:
            totalSilver = totalSilver + 1
            print("silver medal won")
        elif alpha == 3:
            totalBronze = totalBronze + 1
            print("bronze medal won")
        else:
            pass
    else:
        print('is a string')
  print(totalGold, "Gold medals won")
  print(totalSilver, "Silver medals won")
  print(totalBronze, "Bronze medals won")

我的问题是当程序读取一个具有整数的行时，如果该行包含一个整数并且从那里运行相应的if语句，它就不能正确地确定。目前我的输出看起来像这样。

HAJOS
is a string
ALFRED
is a string
1896
is a string
1
is a string

is a string
0 Gold medals won
0 Silver medals won
0 Bronze medals won
done

Answer 1

从文件读取的数据始终将成为字符串。您需要尝试转换这些行，而不是测试它们的类型：

try:
    alpha = int(alpha)
    if alpha == 1:
        totalGold = totalGold + 1
        print("gold medal won")
    elif alpha == 2:
        totalSilver = totalSilver + 1
        print("silver medal won")
    elif alpha == 3:
        totalBronze = totalBronze + 1
        print("bronze medal won")
except ValueError:
    print('is a string')

当int()无法解释为整数时，

ValueError会引发alpha。如果引发异常，则会导致Python跳转到except ValueError:块而不是执行try:套件的其余部分。

Answer 2

你可以制作一个dict，其中键为"1","2" and "3"，对应金，银，铜，并使用dict.get。

with open(infile) as f:
    times = 1
    medal_dict = {"1": 0, "2": 0, "3": 0}
    while times <= 5:
        alpha = f.readline().rstrip()  #reads file line by line#
        times += 1
        if medal_dict.get(alpha) is not None:
            medal_dict[alpha] += 1
        else:
            print("is a string")
    print(medal_dict["1"], "Gold medals won")
    print(medal_dict["2"], "Silver medals won")
    print(medal_dict["3"], "Bronze medals won")

哪个输出：

(1, 'Gold medals won')
(0, 'Silver medals won')
(0, 'Bronze medals won')

如果你想通过循环赢得奖牌时打印：

with open(infile) as f:
    times = 1
    medal_dict = {"1": [0,"gold"], "2": [0,"silver"], "3": [0,"bronze"]}
    while times <= 5:
        alpha = f.readline().rstrip()  #reads file line by line#
        print(alpha)
        times += 1#
        check = medal_dict.get(alpha)
        if check is not None:
            medal_dict[alpha][0] += 1
            print("{} medal won".format(check[1]))
        else:
            print("is a string")
    print(medal_dict["1"][0], "Gold medals won")
    print(medal_dict["2"][0], "Silver medals won")
    print(medal_dict["3"][0], "Bronze medals won")

Python：如何在if语句中使用type函数？

2 个答案: