[英]C memcpy issues with unsigned char array
I have a question about memcpy that I hope someone can answer. 我有一个关于memcpy的问题,希望有人能回答。 Here's a short demonstrative program:
这是一个简短的示范程序:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main (int argc, char **argv){
unsigned char buffer[10];
unsigned short checksum = 0x1234;
int i;
memset(buffer, 0x00, 10);
memcpy(buffer, (const unsigned char*)&checksum, 2);
for(i = 0; i < 10; i ++){
printf("%02x",buffer[i]);
}
printf("\n");
return 0;
}
When I run this program, I get 34120000000000000000. 当我运行这个程序时,我得到34120000000000000000。
My question is why don't I get 12340000000000000000? 我的问题是为什么我得不到12340000000000000000?
Thanks so much 非常感谢
You are getting 34120000000000000000 because you are on a little-endian system. 您将获得34120000000000000000,因为您使用的是小端系统。 You would get 12340000000000000000 on a big-endian system.
您将在big-endian系统上获得12340000000000000000。 Endianness gives a full discussion of big-endian vs. little-endian systems.
Endianness对big-endian系统与little-endian系统进行了全面讨论。
little endian/big endian architecture ? 小端/大端架构? which mean that 2 byte of checksum is inverted.
这意味着2字节的校验和被反转。
It is just a guess, if my answer is not true Comment it and I will delete it. 这只是一个猜测,如果我的答案不是真的那么评论它我将删除它。
Intel's CPUs are little endian, they store numbers little word first 英特尔的CPU是小端,它们首先存储的数字很少
This is apparently evidence that Intel don't do inhouse drug testing. 这显然是英特尔不进行内部药物测试的证据。
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