我有一个奇怪的问题,当我做了一个PWRITE结构到一个文件中。它在结构中的一个char条目旁边添加一个单字节。当我试图单独将char写入文件时,它正确写入了一个字节。有人可以告诉我为什么单个字节被添加?;额外的字节得到写入文件
int main(){
typedef struct pcap_hdr_s {
guint32 magic_number; /* magic number */
guint16 version_major; /* major version number */
guint16 version_minor; /* minor version number */
gint32 thiszone; /* GMT to local correction */
guint32 sigfigs; /* accuracy of timestamps */
guint32 snaplen; /* max length of captured packets, in octets */
guint32 network; /* data link type */
guint32 ts_sec; /* timestamp seconds */
guint32 ts_usec; /* timestamp microseconds */
guint32 incl_len; /* number of octets of packet saved in file */
guint32 orig_len; /* actual length of packet */
guint16 fcf;
char seqno;
guint16 dpan;
guint16 daddr;
guint16 saddr;
gint16 payload_data;
} pcaprec_hdr_t;
pcaprec_hdr_t packet_header;
packet_header.magic_number = PCAP_MAGIC;
packet_header.version_major = 2;
packet_header.version_minor = 4;
packet_header.thiszone = 0;
packet_header.sigfigs = 0;
packet_header.snaplen = 65535;
packet_header.network = 195;
struct timeval tv;
gettimeofday(&tv, NULL);
packet_header.ts_sec = tv.tv_sec;
packet_header.ts_usec = tv.tv_usec;
packet_header.incl_len = 11;
packet_header.orig_len = 13;
packet_header.seqno = 255;
packet_header.dpan = 65535;
packet_header.daddr = 65535;
packet_header.saddr = 65535;
packet_header.payload_data = 8;
int fd = open("sample.cap", O_CREAT | O_WRONLY);
printf("Bytes written: %d \n",pwrite(fd, &packet_header, sizeof(packet_header),0));
}
的结构有一个char变种“序列”和旁边的序列编号值随机值的单字节的文件中被添加。
听起来像一个对准/结构包装问题。 – blueshift