为什么它不会写入文件？

Question

所以我有代码：

def logdata(x, y):
    try:
        f = open('multlog.txt', 'a')
        f.write("{0:g} * {1:g} = {2:g}\n".format(x,y, (x*y)))
    except ValueError:
        f.write("Error, you tried to multiply by something that wasn't a number")
        raise
    finally:
        f.close()
print("This is a test program, it logs data in a text file, 'multlog.txt'")
fn = input("Enter the first number you'd like to multiply by: ")
sn = input("Enter the second number you'd like to multiply by: ")
logdata(int(fn), int(sn))

我想要它做的是，当它到达一个值错误时，它会写入文件，“错误，你试图乘以一个不是数字的东西”。但是，如果用户输入一个字母，比如“j”，ValueError: invalid literal for int() with base 10: 'j'，文件达到值错误，它就不会写入文件！

Answer 1

至少有两个问题：

1. 文件未打开以在except 块中写入（或追加）。
2. 正如@DSM 在评论中指出的那样，当您调用int() 时会引发 ValueError

我会改写成下面的例子。
如果您使用with 语句，那么您可以不使用finally 块。

def logdata(x, y):
    with open('multlog.txt', 'a') as f:
        try:
            x = int(x); y = int(y)
            f.write("{0:g} * {1:g} = {2:g}\n".format(x,y, (x*y)))
        except ValueError:
            f.write("Error")

print("This is a test program, it logs data in a text file, 'multlog.txt'")
fn = input("Enter the first number you'd like to multiply by: ")
sn = input("Enter the second number you'd like to multiply by: ")
logdata(fn, sn)