如何在特定于 python 的 ValueError 中引发？

Question

如果我的 infile 或 outfile 或其中两个为空，我必须引发 ValueError('Invalid file name')

这是python中的代码：

def get_x_freqs(infile, outfile, x):
    # Write the rest of the code for question 3 below here.
    f =None
    try:
        f=open(infile, "r")
        if infile=='':
            raise ValueError('Invalid file name')

        else:
            d={}
            for line in f:
                element = line.split()
                for word in element:
                    d[word]=d.get(word,0)+1

        try:
            f=open(outfile, "w")
            if outfile=='':
                raise ValueError('Invalid file name')
            else:
                sorted_elements = sorted(d.keys(), key=d.get, reverse=True)
                for e in sorted_elements[:x]:
                    print(e, ':', d[e])

        finally:
            if f!= None:
                f.close()


in_filename = 'C:\\Users\\shirl\\Desktop\\מדעים להייטק\\פיתון\\Exercises\\ex.5\\q3.txt'
out_filename = 'C:\\Users\\shirl\\Desktop\\מדעים להייטק\\פיתון\\Exercises\\ex.5\\q3_out.txt'

get_x_freqs(in_filename, out_filename, 3)

Answer 1

你的try-except块应该更像这样：

try:
    f=open(infile, "r")
    d = {}
    for line in f:
        element = line.split()
        for word in element:
            d[word] = d.get(word, 0) + 1
except:
    raise ValueError('Invalid file name')