如何产生以毫秒、微秒为种子的随机数
如题，我的程序短时间内（1秒内）需要产生不同的随机数，如何实现？
srand(time(0)) 和 srand(clock()) 都不够精确。特向各位高手求助，谢谢大家！
因为考虑到跨平台，C++标准（包括STL）里的函数可以实现吗？

[解决办法]
仅供参考

C/C++ code

#include <stdio.h>#include <stdlib.h>#include <string.h>#ifdef WIN32    #include <windows.h>    #include <io.h>#else    #include <unistd.h>    #include <sys/time.h>    #include <pthread.h>    #define  CRITICAL_SECTION   pthread_mutex_t    #define  _vsnprintf         vsnprintf#endif//Log{#define MAXLOGSIZE 100000000#define ARRSIZE(x) (sizeof(x)/sizeof(x[0]))#include <time.h>#include <sys/timeb.h>#include <stdarg.h>char logfilename1[]="MyLog1.log";char logfilename2[]="MyLog2.log";char logstr[16000];char datestr[16];char timestr[16];char mss[4];CRITICAL_SECTION cs_log;FILE *flog;#ifdef WIN32void Lock(CRITICAL_SECTION *l) {    EnterCriticalSection(l);}void Unlock(CRITICAL_SECTION *l) {    LeaveCriticalSection(l);}#elsevoid Lock(CRITICAL_SECTION *l) {    pthread_mutex_lock(l);}void Unlock(CRITICAL_SECTION *l) {    pthread_mutex_unlock(l);}#endifvoid LogV(const char *pszFmt,va_list argp) {    struct tm *now;    struct timeb tb;    if (NULL==pszFmt||0==pszFmt[0]) return;    if (-1==_vsnprintf(logstr,ARRSIZE(logstr),pszFmt,argp)) logstr[ARRSIZE(logstr)-1]=0;    ftime(&tb);    now=localtime(&tb.time);    sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday);    sprintf(timestr,"%02d:%02d:%02d",now->tm_hour     ,now->tm_min  ,now->tm_sec );    sprintf(mss,"%03d",tb.millitm);    printf("%s %s.%s %s",datestr,timestr,mss,logstr);    flog=fopen(logfilename1,"a");    if (NULL!=flog) {        fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr);        if (ftell(flog)>MAXLOGSIZE) {            fclose(flog);            if (rename(logfilename1,logfilename2)) {                remove(logfilename2);                rename(logfilename1,logfilename2);            }            flog=fopen(logfilename1,"a");            if (NULL==flog) return;        }        fclose(flog);    }}void Log(const char *pszFmt,...) {    va_list argp;    Lock(&cs_log);    va_start(argp,pszFmt);    LogV(pszFmt,argp);    va_end(argp);    Unlock(&cs_log);}//Log}int main(int argc,char * argv[]) {    int i;#ifdef WIN32    InitializeCriticalSection(&cs_log);#else    pthread_mutex_init(&cs_log,NULL);#endif    for (i=0;i<10000;i++) {        Log("This is a Log %04d from FILE:%s LINE:%d\n",i, __FILE__, __LINE__);    }#ifdef WIN32    DeleteCriticalSection(&cs_log);#else    pthread_mutex_destroy(&cs_log);#endif    return 0;}
[解决办法]
随机数是rand, 不是srand，谢谢。

linux平台可以读/dev/urandom。