四个或两个字节？ [英] Four or Two Bytes?
问题描述
有人知道以下答案吗？一个unsigned short是2
字节长。为什么以下文件创建为4个字节而不是
2？
file = fopen（" data.bin"，" wb"）;
if（file！= NULL）
{
unsigned short s = 65535;
printf（"无符号短的大小：％d bytes \ n"，sizeof（unsigned
short））; // 2个字节 - 好的
fwrite（& s，sizeof（unsigned short），sizeof（s），file）;
fclose（file）; //文件写成4个字节...嗯
}
- Hahnemann
Hahnemann< ha ************* @ gmail.comwrites：
>有人知道以下答案吗？ unsigned short是2
字节长。为什么将以下文件创建为4个字节而不是
2？
> file = fopen（" data.bin"，" wb"）;
if（file！= NULL）
unsigned short s = 65535;
printf（" unsigned short的大小：％d bytes \ n"，sizeof（unsigned
短））; // 2个字节 - 好的
fwrite（& s，sizeof（unsigned short），sizeof（s），file）;
fclose（file）; //文件写成4个字节...嗯
}
因为你要求它？
检查fwrite（）的第3个参数。
-
克里斯。
5月29日，9：39 * pm，Chris McDonald< ch ... @ csse.uwa.edu.auwrote：
Hahnemann< hahnemann.or ... @ gmail.com写的：
有人知道以下答案吗？一个unsigned short是2
字节长。 *为什么以下文件创建为4个字节而不是
2？
file = fopen（" data.bin"，" wb"）;
if（file！= NULL）
{
* * unsigned short s = 65535;
* * printf（" ;无符号短的大小：％d bytes \ n"，sizeof（unsigned
short））; // 2个字节 - 好的
* * fwrite（& s，sizeof（unsigned short），sizeof（s），file）;
* * fclose（file） ; //文件写成4个字节...嗯
}
因为你要求它？
检查fwrite（）的第3个参数。
-
克里斯。
但请注意：
printf（" s的大小：％d bytes \ n"，sizeof（ s））;
返回2个字节。如何使用以下文件创建2个字节的文件：
unsigned short x = 65535;
这是否可能？
"哈内曼" < ha ************* @ gmail.comwrote in message
news：2f ***************** ***************** @ d1g2000h sg.googlegroups.com ...
有谁知道答案以下？一个unsigned short是2
字节长。为什么以下文件创建为4个字节而不是
2？
file = fopen（" data.bin"，" wb"）;
if（file！= NULL）
{
unsigned short s = 65535;
printf（"无符号短的大小：％d bytes \ n"，sizeof（unsigned
short））; // 2个字节 - OK
fwrite（& s，sizeof（unsigned short），sizeof（s），file）;
fwrite（
指向缓冲区的指示... ok
该缓冲区元素的大小.. .2
要写的元素数量... 2
文件写入句柄应该发生... ok
因此，每个2个字节的2个元素应写入4个字节。
fclose（file）; //文件写为4个字节... hmm
所以，fwrite工作正常。或多或少，因为它从
a 2字节对象中写出了4个字节。它可能很容易就崩溃了超出对象范围的
。
}
- 比尔
Does anybody know the answer to the following? An unsigned short is 2
bytes long. Why is the following file created as 4 bytes instead of
2?
file = fopen("data.bin", "wb");
if (file != NULL)
{
unsigned short s = 65535;
printf("Size of unsigned short: %d bytes\n", sizeof(unsigned
short)); // 2 bytes - OK
fwrite(&s, sizeof(unsigned short), sizeof(s), file);
fclose(file); // File written as 4 bytes... hmm
}
- Hahnemann
Hahnemann <ha*************@gmail.comwrites:
>Does anybody know the answer to the following? An unsigned short is 2
bytes long. Why is the following file created as 4 bytes instead of
2?
>file = fopen("data.bin", "wb");
if (file != NULL)
{
unsigned short s = 65535;
printf("Size of unsigned short: %d bytes\n", sizeof(unsigned
short)); // 2 bytes - OK
fwrite(&s, sizeof(unsigned short), sizeof(s), file);
fclose(file); // File written as 4 bytes... hmm
}
Because you''re asking it to?
Check the 3rd parameter of fwrite().
--
Chris.
On May 29, 9:39*pm, Chris McDonald <ch...@csse.uwa.edu.auwrote:Hahnemann <hahnemann.or...@gmail.comwrites:Does anybody know the answer to the following? An unsigned short is 2
bytes long. *Why is the following file created as 4 bytes instead of
2?
file = fopen("data.bin", "wb");
if (file != NULL)
{
* *unsigned short s = 65535;
* *printf("Size of unsigned short: %d bytes\n", sizeof(unsigned
short)); // 2 bytes - OK
* *fwrite(&s, sizeof(unsigned short), sizeof(s), file);
* *fclose(file); // File written as 4 bytes... hmm
}
Because you''re asking it to?
Check the 3rd parameter of fwrite().
--
Chris.But notice that:
printf("Size of s: %d bytes\n", sizeof(s)) ;
returns 2 bytes. How can I make the file 2 bytes using:
unsigned short x = 65535;
Is this even possible?
"Hahnemann" <ha*************@gmail.comwrote in message
news:2f**********************************@d1g2000h sg.googlegroups.com...Does anybody know the answer to the following? An unsigned short is 2
bytes long. Why is the following file created as 4 bytes instead of
2?
file = fopen("data.bin", "wb");
if (file != NULL)
{
unsigned short s = 65535;
printf("Size of unsigned short: %d bytes\n", sizeof(unsigned
short)); // 2 bytes - OK
fwrite(&s, sizeof(unsigned short), sizeof(s), file);fwrite(
pointer to buffer ... ok
size of an element of that buffer ... 2
number of elements to write ... 2
handle for file write should occur to ... ok
So, 2 elements of 2 bytes each should write four bytes.
fclose(file); // File written as 4 bytes... hmmSo, fwrite worked correctly. More or less, since it wrote out 4 bytes from
a 2 byte object. It could just about as easily have crashed when it went
beyond the bounds of the object.
}- Bill
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