Question

我在使用python将字符串写入文件时遇到问题：（我要做的是使用python生成一些C程序）我的代码如下：

filename = "test.txt"
i = 0
string = "image"
tempstr = ""
average1 = "average"
average2 = "average*average"
output = ""
FILE = open(filename,"w")
while i < 20:
    j = 0
    output = "square_sum = square_sum + "
    while j < 20:        
        tempstr = string + "_" + str(i) + "_" + str(j)        
        output = output + tempstr + "*" + tempstr + " + " + average2 + " - 2*" + average1 + "*" + tempstr        
        if j != 19:        
            output = output + " + "
        if j == 19:
            output = output + ";"        
        j = j + 1
    output = output + "\n"
    i = i + 1
    print(output)
    FILE.writelines(output)    
FILE.close

打印给了我正确的输出，但是FILE的最后一行缺失，而第二行的一些缺失。将字符串写入文件有什么问题？

谢谢！

Answer 1

如果你打电话给方法，可能会有帮助...

FILE.close()

Answer 2

问题是你没有调用close()方法，只是在最后一行提到它。你需要parens来调用一个函数。

Python的with语句可以使其不必要：

with open(filename,"w") as the_file:
    while i < 20:
        j = 0
        output = "square_sum = square_sum + "
        ...
        print(output)
        the_file.writelines(output)

退出with子句后，the_file将自动关闭。

Answer 3

尝试：

with open(filename,"w") as FILE:
    while i < 20:
        # rest of your code with proper indent...

不需要关闭...

Answer 4

首先，代码的Python化版本：

img = 'image_{i}_{j}'
avg = 'average'
clause = '{img}*{img} + {avg}*{avg} - 2*{avg}*{img}'.format(img=img, avg=avg)
clauses = (clause.format(i=i, j=j) for i in xrange(20) for j in xrange(20))
joinstr = '\n    + '
output = 'square_sum = {};'.format(joinstr.join(clauses))

fname = 'output.c'
with open(fname, 'w') as outf:
    print output
    outf.write(output)

其次，看起来你希望通过狂热的内联来加速你的C代码。我非常怀疑速度提升将证明你的努力是合理的

maxi = 20;
maxj = 20;
sum = 0;
sqsum = 0;
for(i=0; i<maxi; i++)
    for(j=0; j<maxj; j++) {
        t = image[i][j];
        sum += t;
        sqsum += t*t;
    }

square_sum = sqsum + maxi*maxj*average*average - 2*sum*average;

Answer 5

看起来您的缩进可能不正确，但只是其他一些关于您的代码的评论：

writelines()将列表或迭代器的内容写入文件。由于输出单个字符串，只需使用write()。

lines ["lineone\n", "line two\n"]
f = open("myfile.txt", "w")
f.writelines(lines)
f.close()

或者只是：

output = "big long string\nOf something important\n"
f = open("myfile.txt", "w")
f.write(output)
f.close()

另一方面注意，使用+=运算符可能会有所帮助。

output += "more text"
# is equivalent to
output = output + "more text"

Python写入文件缺少行

5 个答案: