Python：如何在if语句中使用类型函数？

我正在编写一个从文件中加载数据列表的程序，我需要该程序来区分行中的数据是字符串还是整数。然而，在我编写的代码中，程序没有区分数字和字符串

我拥有的数据列表示例如下：

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")

从文件中读取的数据总是字符串。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')

---

int（）

将在无法将

alpha

解释为整数时引发

ValueError

。如果引发异常，则会导致Python跳转到

除ValueError:

块，而不是执行

try:

套件的其余部分。

您可以制作一个dict，其中键是

“1”、“2”和“3”

，对应于金、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")

如果要在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")

打开（填充）为f:
次数=1
奖牌名称={“1”：[0，“金”]，“2”：[0”，“银”]，“3”：[0”，“铜”}
当输出显示时间时，所有值实际上都是字符串。当您从这样的文件中读取数据时，您总是在读取字符串。如果你想把它们转换成整数，你需要自己去做。提示：
int（alpha）
将
alpha
转换成整数，或者如果不能的话抛出一个
ValueError
。
如果alpha.isdigit（）
也会比我（现在已删除）的答案好很多。。。阅读问题的方式…：P+1@JoranBeasley：将问题编辑成某种形状有助于理解。：-）我只是试着在我的代码中实现它，它在很大程度上起了作用。不过，唯一的问题是，如果使用它，无论如何都不会更新获得的奖牌总数。但是，它确实正确地将字符串转换为整数。编辑：没关系，我只是有个语法错误。
(1, 'Gold medals won')
(0, 'Silver medals won')
(0, 'Bronze medals won')

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")