将int写入文件，不太确定缓冲区如何工作。 [英] Writing an int to a file, not quite sure how buffers work.
问题描述
我想写一个int到一个文件，到目前为止我已写过：
const char buff [20];
int num = 256 //为了这个例子
sprintf（buff，"％d"，num）;
现在我的问题是什么做下一个。我可以使用fwrite，但我不知道
了解大小是如何工作的，我不确定它是否写出了整个
缓冲区，以及我绝对只想写出256。
我可以使用putc通过缓冲区并一次写出一个字符
，但同样的问题，我不知道是否写出了整个20
字符缓冲区或在''256'后停止。
我没有必要长时间使用这些东西，而且我完全不知道
忘记这个缓冲区的工作方式，我发现它很烦人
to必须事先分配空间。
I''m wanting to write an int to a file, and so far I have written:
const char buff[20];
int num = 256 //for the sake of the example
sprintf(buff, "%d", num);
Now my question is what to do next. I could use fwrite, but I don''t
understand how the size works, I''m not sure if it writes out the whole
buffer or not, and I definetly only want to write out "256."
I could use putc to go through the buffer and write out one character
at a time, but same issue, I don''t know if that writes out the whole 20
character buffer or stops after the ''256''.
I haven''t had to use this stuff for a long time, and I completely
forget how this buffer stuff works and I''m finding it fairly annoying
to have to allot the space beforehand.
推荐答案
me ********** @ yahoo.ca 写道：
我想写一个文件的int，到目前为止我写的：
const char buff [20];
int num = 256 // for例子的缘故
sprintf（buff，"％d"，num）;
I''m wanting to write an int to a file, and so far I have written:
const char buff[20];
int num = 256 //for the sake of the example
sprintf(buff, "%d", num);
为什么你不使用fprintf？
-
Ian Collins。
Why don''t you use fprintf?
--
Ian Collins.
为什么你不使用fprintf？
-
Ian Collins。
Why don''t you use fprintf?
--
Ian Collins.
好的。我还是不知道缓冲区是如何工作的。它打印出
整个缓冲区还是只是我放入的int？
假设我写道：
fprintf（outputfile，"％d"，buff）;
Ok. I still don''t know how the buffer works. Does it print out the
entire buffer or just the int I have placed in it?
Supposing I wrote:
fprintf(outputfile, "%d",buff);
me ********** @ yahoo.ca 写道：
>
>
>>为什么你不使用fprintf？
>>Why don''t you use fprintf?
好的。我还是不知道缓冲区是如何工作的。它打印出
整个缓冲区还是只是我放入的int？
假设我写道：
fprintf（outputfile，"％d"，buff）;
Ok. I still don''t know how the buffer works. Does it print out the
entire buffer or just the int I have placed in it?
Supposing I wrote:
fprintf(outputfile, "%d",buff);
请保留足够的背景和旅行签名。
鉴于buff是一个char []（你写了const char []，你不能写入
），你会得到不确定的行为。
如果你写了
fprintf（outputfile，"％s"，buff）;
你会得到相同的您可以在控制台上找到文件
你写的
printf（"％s"，buff）;
-
Ian Collins。
Please keep enough context and trip signatures.
Given buff is a char[] (you wrote const char[], which you can''t write
into), you get undefined behaviour.
If you had written
fprintf(outputfile, "%s", buff);
you would get the same in the file as you would get on you console had
you written
printf("%s", buff);
--
Ian Collins.
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