C - 为什么我的缓冲区打印不正确? [英] C - Why is my buffer not printing properly?
问题描述
我有两个对象,Header和DF。
可以说
header = CCCCCC7E
和
DF = 01020304
,
不应该缓冲区的值是 CCCCCC7E01020304
?
由于某些原因,当我印刷它时,我得到了:
$ p $ 7EFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCC00FFFF
FFCC00000000000004030201FFFFFF8967341200000000
这就是我的印刷方式:
for(int i = 0; i< sizeof(buffer); i ++)
{printf(%02X,buffer [i]); }
这是代码:
struct头部标题;
struct Data_Format DF;
unsigned char buffer [TOTAL_SIZE];
header.Start = 0x7E;
header.Options = 0x00;
header.PacketLength = 0x00;
header.VCP = 0x00;
header.Reserved = 0x00;
header.Return = 0x00;
DF.Address = 0x01020304; //真实值:NULL
DF.Result = 0x1234; //真实值:NULL
DF.Size = 0x6789; //真实值:NULL
memcpy(buffer,& header,sizeof(Header));
memcpy(buffer + sizeof(Header),& DF,sizeof(Data_Format));
想法,但有一点需要做。
在应对缓冲区之前始终执行memset。
memset(buffer,0,sizeof(buffer))
你得到垃圾。
I have two objects, Header, and DF. lets say
header = CCCCCC7E
and
DF = 01020304
,
shouldnt the value of the buffer be CCCCCC7E01020304
?
for some reason when i printed it i got:
7EFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCCFFFFFFCC00FFFF
FFCC00000000000004030201FFFFFF8967341200000000
this is how i printed it:
for (int i = 0; i < sizeof(buffer); i++)
{ printf("%02X", buffer[i]); }
this is the code:
struct Header header;
struct Data_Format DF;
unsigned char buffer[TOTAL_SIZE];
header.Start = 0x7E;
header.Options = 0x00;
header.PacketLength = 0x00;
header.VCP = 0x00;
header.Reserved = 0x00;
header.Return = 0x00;
DF.Address = 0x01020304; //real value: NULL
DF.Result = 0x1234; //real value: NULL
DF.Size = 0x6789; //real value: NULL
memcpy(buffer,&header, sizeof(Header));
memcpy(buffer+sizeof(Header), &DF, sizeof(Data_Format));
From the partial code given it doesn't give much idea but Some point need to do.
Do a memset always before coping to the buffer.
memset(buffer, 0, sizeof(buffer))
This will prevent you to get the junk.
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