blocks|key|1292417|text|你没有说文件的格式是什么。根据您的尝试，我假设您的文件每行只包含一个整数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1292418|以下是您的函数的一些问题：|1292419|1292420|您正在向名为l的函数传递参数，但没有使用它。您应该使用它作为要打开的文件的名称，而不是硬编码'even.txt'.|unordered-list-item|offset|length|style|CODE|1292421|You将整个文件读取到一个名为num的变量中，然后甚至不使用该变量。读取完整个文件后，在|1292422|循环中就没有什么可迭代的了。|1292423|+for循环以字符串的形式遍历文件的各行。在测试它是否能被2整除之前，你需要将它转换成一个整数。|1292424|在for循环中，你将返回找到的第一个偶数，而不是计算所有的偶数。您需要在循环之前创建一个计数变量，并在每次找到偶数时在循环中递增，然后在循环完成后返回计数。|1292425|1292426|如果你解决了这些问题，你的函数应该是这样的：|1292427|def+counteven(filename):
++countOfEvenNumbers+=+0
++infile+=+open(filename,+'r')
++for+line+in+infile:
++++number+=+int(line)
++++if+(number+%252+==+0):
++++++countOfEvenNumbers%2B=+1
++infile.close()
++return+countOfEvenNumbers|code-block|syntax|javascript|1292428|..。|1292429|更新(回复您的评论)：|BOLD|1292430|assertEqual是unittest模块提供的TestCase类的方法。如果您正在编写单元测试，那么应该在从TestCase派生的类的测试用例中调用assertEqual。|1292431|如果你只是想在单元测试之外创建一个断言，你可以这样写：|1292432|assert+counteven('even.txt')+==+2,+'+Number+of+even+numbers+must+be+2'|1292433|entityMap^0|0|0|0|6|1|1A|A|0|F|3|0|0|1|3|0|1|3|0|0|0|0|0|0|2|0|0|B|C|8|P|8|1K|8|24|B|0|0|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|1H|8|@$H|1I|I|1J|J|K]|$H|1K|I|1L|J|K]]|9|@]|A|$]]|$1|L|3|M|5|G|7|1M|8|@$H|1N|I|1O|J|K]]|9|@]|A|$]]|$1|N|3|O|5|6|7|1P|8|@]|9|@]|A|$]]|$1|P|3|Q|5|G|7|1Q|8|@$H|1R|I|1S|J|K]]|9|@]|A|$]]|$1|R|3|S|5|G|7|1T|8|@$H|1U|I|1V|J|K]]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1W|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1X|8|@]|9|@]|A|$]]|$1|W|3|X|5|Y|7|1Y|8|@]|9|@]|A|$Z|10]]|$1|11|3|12|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|20|8|@$H|21|I|22|J|15]]|9|@]|A|$]]|$1|16|3|17|5|6|7|23|8|@$H|24|I|25|J|K]|$H|26|I|27|J|K]|$H|28|I|29|J|K]|$H|2A|I|2B|J|K]|$H|2C|I|2D|J|K]]|9|@]|A|$]]|$1|18|3|19|5|6|7|2E|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|Y|7|2F|8|@]|9|@]|A|$Z|10]]|$1|1C|3|-4|5|6|7|2G|8|@]|9|@]|A|$]]]|1D|$]]

You do not say what the format of the file is. Based on your attempt, I'm assuming that your file contains just a single integer on each line.

Here are some of the problems with your function:

<ul>
<li>You are passing an argument to the function called <code>l</code>, but not using it. You should be using it as the name of the file to open, instead of hard coding <code>'even.txt'</code>.</li>
<li>You are reading the entire file into a variable called <code>num</code> and then do not even use that variable. Having read in the entire file, there is nothing left to iterate over in your for loop.</li>
<li>Your <code>for</code> loop iterates over the lines of the file as strings. You need to convert the line to an integer before testing if it's divisible by two.</li>
<li>Inside the <code>for</code> loop, you are going to return the first even number found, rather than counting all the even numbers. You need to create a count variable before the loop, and increment in the loop every time an even number is found, then return the count after the loop has completed.</li>
</ul>

If you fix those problems, your function should look something like this:

<pre><code>def counteven(filename):
 countOfEvenNumbers = 0
 infile = open(filename, 'r')
 for line in infile:
 number = int(line)
 if (number %2 == 0):
 countOfEvenNumbers+= 1
 infile.close()
 return countOfEvenNumbers
</code></pre>

...

UPDATE (to address your comment):

<code>assertEqual</code> is a method of the <code>TestCase</code> class provided by the <code>unittest</code> module.
If you are writing a unit test, then <code>assertEqual</code> should be called in a test case in a class derived from <code>TestCase</code>.

If you simply want to make an assertion ouside of a unit test you can write:

<pre><code>assert counteven('even.txt') == 2, ' Number of even numbers must be 2'
</code></pre>

blocks|key|1286232|text|@Ergwun+pointed+out已经指出了你代码中的问题。这里有另一个解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1286233|def+counteven(integers):
++++return+sum(1+for+n+in+integers+if+n+%25+2+==+0)

with+open('even.txt')+as+f:
++++numbers+=+(int(line)+for+line+in+f)
++++print(counteven(numbers))|code-block|syntax|javascript|1286234|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/5657154/can-any-one-figure-this-out-using-python/5657367#5657367^0|8|B|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

@Ergwun <a href="https://stackoverflow.com/questions/5657154/can-any-one-figure-this-out-using-python/5657367#5657367">pointed out</a> already the problems in your code. Here's another solution:

<pre><code>def counteven(integers):
 return sum(1 for n in integers if n % 2 == 0)

with open('even.txt') as f:
 numbers = (int(line) for line in f)
 print(counteven(numbers))
</code></pre>

Write a function that takes as argument, a filename to read, returns the number of even numbers present in the file.

I have tried and tried please some one help. it does not return the the even numbers.

<pre><code>def counteven(l):
 infile = open('even.txt', 'r')
 num = infile.read()
 for i in infile:
 if (i %2!=0):
 return i

 infile.close()

assertEqual(counteven('even.txt'),2)
</code></pre>

Count even numbers in a file using Python

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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编写一个函数，该函数以要读取的文件名作为参数，返回文件中存在的偶数的个数。我试了又试，请帮帮忙。它不返回偶数。def counteven(l):    infile = open('even.txt', 'r')    num = infile.read()    for i in infile:        if ...

问使用Python计算文件中的偶数
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