字节数组长？ [英] byte array and long??
问题描述
你好！
我有以下情况：
我有一个字节数组，在某个位置存储4个字节，并且
这些应该是放。到长变量（或任何其他4字节一个）。
ie：
byte a [] = {0x0,0x0,0xfe，0x30,0x9e，0x2,0x66， 0,0
和字节0xfe，0x30,0x9e，0x2应该放入长变量，
应该包含43921662
如何要实现这个目标吗？
谢谢！
hello!
I have a following situation:
I have a byte array where at a certain location are stored 4 bytes, and
these should be "put" into long variable (or any other 4 byte one).
ie:
byte a[]={0x0,0x0,0xfe,0x30,0x9e,0x2,0x66,0,0}
and the bytes 0xfe,0x30,0x9e,0x2 should be put into long variable which
should then contain 43921662
how to achieve this?
thanks!
推荐答案
" w3r3w0lf" ; <关于** @ asdf.asdf>在消息中写道
新闻：bv ********** @ ls219.htnet.hr ...
"w3r3w0lf" <as**@asdf.asdf> wrote in message
news:bv**********@ls219.htnet.hr...
你好！
我有一个以下情况：
我有一个字节数组，在某个位置存储4个字节，并且
这些应该是put。到长变量（或任何其他4字节一个）。
即：
字节a [] = {0x0,0x0,0xfe，0x30,0x9e，0x2,0x66,0,0}
并且字节0xfe，0x30,0x9e，0x2应该放入长变量，然后
应该包含43921662
如何实现这个？
谢谢！
hello!
I have a following situation:
I have a byte array where at a certain location are stored 4 bytes, and
these should be "put" into long variable (or any other 4 byte one).
ie:
byte a[]={0x0,0x0,0xfe,0x30,0x9e,0x2,0x66,0,0}
and the bytes 0xfe,0x30,0x9e,0x2 should be put into long variable which
should then contain 43921662
how to achieve this?
thanks!
这个*可能*工作，
long x = * reinterpret_cast< long *>（a + 2）;
但是如果它不是因为你必须交换周围的字节。
byte tmp [4] = {a [5]，a [ 4]，a [3]，a [2]}; //交换字节
long x = * reinterpret_cast< long *>（tmp）;
john
This *might* work,
long x = *reinterpret_cast<long*>(a + 2);
but if it doesn''t it is because you have to swap the bytes around.
byte tmp[4] = { a[5], a[4], a[3], a[2] }; // swap bytes
long x = *reinterpret_cast<long*>(tmp);
john
2004年2月3日星期二22:28:38 -0000，John Harrison
< jo ************* @ hotmail。 COM>在comp.lang.c ++中写道：
On Tue, 3 Feb 2004 22:28:38 -0000, "John Harrison"
<jo*************@hotmail.com> wrote in comp.lang.c++:
" w3r3w0lf" <关于** @ asdf.asdf>在消息中写道
新闻：bv ********** @ ls219.htnet.hr ...
"w3r3w0lf" <as**@asdf.asdf> wrote in message
news:bv**********@ls219.htnet.hr...
你好！
我有以下情况：<我有一个字节数组，在某个位置存储4个字节，并且这些应该是put。到长变量（或任何其他4字节一个）。
即：
字节a [] = {0x0,0x0,0xfe，0x30,0x9e，0x2,0x66,0,0}
并且字节0xfe，0x30,0x9e，0x2应该放入长变量，然后
应该包含43921662
如何实现这个？
谢谢！
hello!
I have a following situation:
I have a byte array where at a certain location are stored 4 bytes, and
these should be "put" into long variable (or any other 4 byte one).
ie:
byte a[]={0x0,0x0,0xfe,0x30,0x9e,0x2,0x66,0,0}
and the bytes 0xfe,0x30,0x9e,0x2 should be put into long variable which
should then contain 43921662
how to achieve this?
thanks!
这*可能*工作，
长x = * reinterpret_cast< long *>（a + 2）;
但如果它没有''这是因为你必须交换周围的字节。
字节tmp [4] = {a [5]，a [4]，a [3]，a [2]}; //交换字节
long x = * reinterpret_cast< long *>（tmp）;
john
This *might* work,
long x = *reinterpret_cast<long*>(a + 2);
but if it doesn''t it is because you have to swap the bytes around.
byte tmp[4] = { a[5], a[4], a[3], a[2] }; // swap bytes
long x = *reinterpret_cast<long*>(tmp);
john
但它会由于不正确的对齐而导致ARM（以及其他一些处理器）因故障而导致故障处理失败。
因为长期意愿，它将在TI 320F28xx上失败包含0x003000fe
这不是OP所要求的。
实际上它在任何
平台上都是未定义的行为/建筑/实施。
-
Jack Klein
主页： http://JK-Technology.Com
comp.lang.c的常见问题解答 http://www.eskimo.com/~scs/ C-faq / top.html
comp.lang.c ++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c ++
<一个rel =nofollowhref =http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html\"target =_ blank> http：//www.contrib.andrew.cmu .edu / ~a ... FAQ-acllc.html
But it will fail on an ARM (and some other processors) with an
addressing fault due to improper alignment.
It will fail on a TI 320F28xx because the long will contain 0x003000fe
which is not what the OP asked for.
And in fact it is undefined behavior on any
platform/architecture/implementation.
--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c++
http://www.contrib.andrew.cmu.edu/~a...FAQ-acllc.html
" w3r3w0lf" <关于** @ asdf.asdf>在消息中写道
新闻：bv ********** @ ls219.htnet.hr ...
"w3r3w0lf" <as**@asdf.asdf> wrote in message
news:bv**********@ls219.htnet.hr...
你好！
我有一个以下情况：
我有一个字节数组，在某个位置存储4个字节，并且
这些应该是put。到长变量（或任何其他4字节一个）。
即：
字节a [] = {0x0,0x0,0xfe，0x30,0x9e，0x2,0x66,0,0}
并且字节0xfe，0x30,0x9e，0x2应该放入长变量中，然后
应该包含43921662
如何实现这个？
谢谢！
hello!
I have a following situation:
I have a byte array where at a certain location are stored 4 bytes, and
these should be "put" into long variable (or any other 4 byte one).
ie:
byte a[]={0x0,0x0,0xfe,0x30,0x9e,0x2,0x66,0,0}
and the bytes 0xfe,0x30,0x9e,0x2 should be put into long variable which
should then contain 43921662
how to achieve this?
thanks!
尝试这个并告诉我它是否有效！
#include< iostream>
使用namespace std;
int main（）{
char a [] = {0x0,0x0,0xfe，0x30,0x9e，0x2,0x66,0， 0};
长b = 0;
memcpy（& b，& a [2]，sizeof（4））;
cout<< b<< endl;
cin.get（）;
}
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try this and tell me if this works!
#include <iostream>
using namespace std;
int main(){
char a[] = {0x0,0x0,0xfe,0x30,0x9e,0x2,0x66,0,0};
long b=0;
memcpy(&b,&a[2], sizeof(4));
cout << b << endl;
cin.get();
}
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