Jiang's C++ Space

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偶尔发现Windows Mobile连一些标准的C语言库函数都没有实现,而这些函数的在头文件中的声明却是有的,实在有些不方便,上网一搜索,才知道原来Windows CE也没实现,而Windows Mobile这方面照搬了Windows CE的,如果真要用这些函数,只能自己来写了,我写了这几个:gmtime,localtime,mktime,strftime,其中用到了Variant Time这个类型,它实质上是个浮点数,浮点数就意味着有时候不太精确,我实践下来确实发觉有时候会有1秒钟的偏差,在计算time_t的时候,不过暂时懒得去管它了。使用方法很简单,把代码复制一份,保存到一个叫“TimeFunctions.cpp”的文件中去,然后在你的project中添加这个文件即可。

#include <time.h>
#include 
<windows.h>

static BOOL IsLeapYear(WORD nYear)
{
    
return !(nYear % 4&& (nYear % 100|| !(nYear % 400);
}

static int DaysFromJan1st(WORD wYear, WORD wMonth)
{
    
static WORD monthday[] = {0315990120151181212243273304334};
    
return monthday[wMonth - 1+ (IsLeapYear(wYear) && wMonth > 2 ? 1 : 0);
}

static tm* GetTmByVariant(DOUBLE dTime)
{
    SYSTEMTIME stResult;
    VariantTimeToSystemTime(dTime, 
&stResult);
    
static tm s_tm;
    s_tm.tm_sec 
= stResult.wSecond;
    s_tm.tm_min 
= stResult.wMinute;
    s_tm.tm_hour 
= stResult.wHour;
    s_tm.tm_mday 
= stResult.wDay;
    s_tm.tm_mon 
= stResult.wMonth-1;
    s_tm.tm_year 
= stResult.wYear-1900;
    s_tm.tm_wday 
= stResult.wDayOfWeek;
    s_tm.tm_yday 
= DaysFromJan1st(stResult.wYear, stResult.wMonth);
    s_tm.tm_isdst 
= 0;
    
return &s_tm;
}

const DOUBLE VT_SECOND_1970 = 2209161600.0;
const DOUBLE SECONDS_IN_ONE_DAY = 86400;

tm
* __cdecl gmtime(const time_t* pTT)
{
    
return GetTmByVariant((VT_SECOND_1970 + (*pTT))/SECONDS_IN_ONE_DAY);
}

tm
* __cdecl localtime(const time_t* pTT)
{
    TIME_ZONE_INFORMATION tz;
    GetTimeZoneInformation(
&tz);
    
return GetTmByVariant((VT_SECOND_1970 + (*pTT) - tz.Bias*60)/SECONDS_IN_ONE_DAY);
}

time_t __cdecl mktime(tm
* pTM)
{
    SYSTEMTIME stToConvert 
= {
        pTM
->tm_year+1900,
        pTM
->tm_mon+1,
        pTM
->tm_wday,
        pTM
->tm_mday,
        pTM
->tm_hour,
        pTM
->tm_min,
        pTM
->tm_sec,
        
0};
    DOUBLE dToCal;
    SystemTimeToVariantTime(
&stToConvert, &dToCal);
    
return (time_t)(dToCal*SECONDS_IN_ONE_DAY - VT_SECOND_1970);
}

static void strfmt(char *str, const char *fmt, )
{
    
int ival, ilen;
    
char *sval;
    
static int pow[5= { 110100100010000 };
    va_list vp;

    va_start(vp, fmt);
    
while (*fmt)
    {
        
if (*fmt++ == '%')
        {
            ilen 
= *fmt++ - '0';
            
if (ilen == 0)                // zero means string arg
            {
                sval 
= va_arg(vp, char*);
                
while (*sval)
                    
*str++ = *sval++;
            }
            
else                          // always leading zeros
            {
                ival 
= va_arg(vp, int);
                
while (ilen)
                {
                    ival 
%= pow[ilen--];
                    
*str++ = (char)('0' + ival / pow[ilen]);
                }
            }
        }
        
else  *str++ = fmt[-1];
    }
    
*str = '\0';
    va_end(vp);
}

#define DAYSPERWEEK 7

size_t __cdecl strftime(
char* pTimeStr, size_t stStrLen, const char* pFmt, const tm* pTM)
{
    
static char *aday[] = {"Sun""Mon""Tue""Wed""Thu""Fri""Sat"};
    
static char *day[] = {"Sunday""Monday""Tuesday""Wednesday""Thursday""Friday""Saturday"};
    
static char *amonth[] = {"Jan""Feb""Mar""Apr""May""Jun""Jul""Aug""Sep""Oct""Nov""Dec"};
    
static char *month[] = {"January""February""March""April""May""June""July""August""September""October""November""December"};

    
int            w;
    
char        *p, *q, *r;
    
static char    buf[26];

    p 
= pTimeStr;
    q 
= pTimeStr + stStrLen - 1;
    
while ((*pFmt != '\0'))
    {
        
if (*pFmt++ == '%')
        {
            r 
= buf;
            
switch (*pFmt++)
            {
            
case '%' :
                r 
= "%";
                
break;

            
case 'a' :
                r 
= aday[pTM->tm_wday];
                
break;

            
case 'A' :
                r 
= day[pTM->tm_wday];
                
break;

            
case 'b' :
                r 
= amonth[pTM->tm_mon];
                
break;

            
case 'B' :
                r 
= month[pTM->tm_mon];
                
break;

            
case 'c' :
                strfmt(r, 
"%0 %0 %2 %2:%2:%2 %4",
                    aday[pTM
->tm_wday], amonth[pTM->tm_mon],
                    pTM
->tm_mday,pTM->tm_hour, pTM->tm_min,
                    pTM
->tm_sec, pTM->tm_year+1900);
                
break;

            
case 'd' :
                strfmt(r,
"%2",pTM->tm_mday);
                
break;

            
case 'H' :
                strfmt(r,
"%2",pTM->tm_hour);
                
break;

            
case 'I' :
                strfmt(r,
"%2",(pTM->tm_hour%12)?pTM->tm_hour%12:12);
                
break;

            
case 'j' :
                strfmt(r,
"%3",pTM->tm_yday+1);
                
break;

            
case 'm' :
                strfmt(r,
"%2",pTM->tm_mon+1);
                
break;

            
case 'M' :
                strfmt(r,
"%2",pTM->tm_min);
                
break;

            
case 'p' :
                r 
= (pTM->tm_hour>11)?"PM":"AM";
                
break;

            
case 'S' :
                strfmt(r,
"%2",pTM->tm_sec);
                
break;

            
case 'U' :
                w 
= pTM->tm_yday/7;
                
if (pTM->tm_yday%7 > pTM->tm_wday)
                    w
++;
                strfmt(r, 
"%2", w);
                
break;

            
case 'W' :
                w 
= (pTM->tm_yday + DAYSPERWEEK -
                    (pTM
->tm_wday ?
                    (pTM
->tm_wday - 1) :
                (DAYSPERWEEK 
- 1))) / DAYSPERWEEK;
                strfmt(r, 
"%2", w);
                
break;

            
case 'w' :
                strfmt(r,
"%1",pTM->tm_wday);
                
break;

            
case 'x' :
                strfmt(r, 
"%2/%2/%2", pTM->tm_mon + 1,
                    pTM
->tm_mday, pTM->tm_year+1900);
                
break;

            
case 'X' :
                strfmt(r, 
"%2:%2:%2", pTM->tm_hour,
                    pTM
->tm_min, pTM->tm_sec);
                
break;

            
case 'y' :
                strfmt(r,
"%2",pTM->tm_year%100);
                
break;

            
case 'Y' :
                strfmt(r,
"%4",pTM->tm_year+1900);
                
break;

            
case 'Z' :
//                r = (pTM->tm_isdst && tz_name[1][0])?tz_name[1]:tz_name[0];
                break;

            
default:
                buf[
0= '%';        // reconstruct the format
                buf[1= pFmt[-1];
                buf[
2= '\0';
                
if (buf[1== 0)
                    pFmt
--;            // back up if at end of string
            }
            
while (*r)
            {
                
if (p == q)
                {
                    
*= '\0';
                    
return 0;
                }
                
*p++ = *r++;
            }
        }
        
else
        {
            
if (p == q)
            {
                
*= '\0';
                
return 0;
            }
            
*p++ = pFmt[-1];
        }
    }
    
*= '\0';
    
return p - pTimeStr;
}


posted on 2011-06-30 16:45 Jiang Guogang 阅读(1975) 评论(2)  编辑 收藏 引用 所属分类: Windows Embedded Programming

评论

# re: 帮Windows Mobile实现gmtime,localtime,mktime和strftime 2011-07-01 09:42 gejun
唉,真是又当爹又当妈啊,还是逃离winmobile吧  回复  更多评论
  

# re: 帮Windows Mobile实现gmtime,localtime,mktime和strftime 2014-09-11 20:30 hotman_x
拿走。
谢了。  回复  更多评论
  


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