很多情況導致電腦開機后總是從00:00開始，如主板CMOS電池供電不足。時間不對有時會導致網絡瀏覽提示日期沒有更新而不能正常訪問。雖然Windows系統也有同步到internet時間的操作界面，需要多次點擊。但如果是舊電腦，每次開機都要去更新這個時間，非常繁瑣。所以，可以寫一個自動將本地時間同步到網絡時間的小程序。

1 C語言如何設置Windows平臺的本地時間

1.1 C語言Windows時鐘的結構體如下：

typedef struct _SYSTEMTIME {WORD wYear;/*年*/WORD wMonth; /*月*/WORD wDayOfWeek; /*星期0-60-Sunday...*/WORD wDay;/*日*/WORD wHour;/*時*/WORD wMinute;/*分*/WORD wSecond;/*秒*/WORD wMilliseconds;/*微妙*/} SYSTEMTIME, *PSYSTEMTIME;

1.2 設置本地時間的API

windows.h提供的函數SetLocalTime()可以設置本地時間。

BOOL WINAPI SetLocalTime(_In_const SYSTEMTIME *lpSystemTime);

其參數就是上述的結構體指針。

_In_在visual C++中屬于SAL批注，是為了編譯系統在分析代碼時發現缺陷用的。表示是一個輸入參數。類似的還有_Out_。

2 獲取某些網站頁面返回的時間字符串

如以下站點

http://quan.suning.com/getSysTime.do

頁面顯示：

{"sysTime2":"2022-08-10 08:40:08","sysTime1":"20220810084008"}

通過socket套接字編程即可提取到該頁面返回的字符串，如：

19,36,200-0,M], cache20.cn3603[43,0]

X-Cache: MISS TCP_MISS dirn:-2:-2

X-Swift-SaveTime: Wed, 10 Aug 2022 00:50:57 GMT

X-Swift-CacheTime: 0

Timing-Allow-Origin: *

EagleId: 708422a816600926577736154e

{"sysTime2":"2022-08-10 08:50:57","sysTime1":"20220810085057"}-cache,no-store,ma

x-age=0,s-maxage=0

Access-Control-Allow-Credentials: true

es-suning-dnsstr: quan.suning.com:tradema:default

Ali-Swift-Global-Savetime: 1660092657

Via: cache46.l2cn3036[8,10,200-0,M], cache79.l2cn3036[12,0], cache3.cn3603[…

3 提取需要的字符串

4 調用SetLocalTime()設置本地時間

code demo:

#include #include #include #include #pragma comment(lib, "ws2_32.lib")/* * 國家授時中心 http://www.ntsc.ac.cn/ * 獲取網絡時間的網站API * 蘇寧 http://quan.suning.com/getSysTime.do  * 淘寶 http://api.m.taobao.com/rest/api3.do?api=mtop.common.getTimestamp * QQhttp://cgi.im.qq.com/cgi-bin/cgi_svrtime**/ｃｈａｒ* getTimeTxt(ｃｈａｒ *url);int set_local_time(const ｃｈａｒ *timeStr);int main() {ｃｈａｒ * time = getTimeTxt("quan.suning.com/getSysTime.do");if(time==NULL){printf("返回的是亂字符串！\n");printf("3秒后自動關閉窗口……");Sleep(3000);exit(1);}printf("正在應用設置...\n");//strcpy(time,"20220807174237");//printf("%s\n",time);if(set_local_time(time)==0)printf("設置時間成功！\n\n");elseprintf("設置時間失敗，可能是沒有權限");printf("3秒后自動關閉窗口……");Sleep(3000);//getTimeTxt("api.mmuaa.com/gettime");//getchar();return 0;}ｃｈａｒ* getTimeTxt(ｃｈａｒ *url) {WSADATA WSAData= {0};if(WSAStartup(MAKEWORD(2,2), &WSAData)) {// WSAStartupprintf("WSA 失敗!\n");return false;}SOCKETsockfd;sockfd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP); // socket ｃｈａｒ myurl[BUFSIZ];strcpy(myurl, url);ｃｈａｒ *pHost = 0;ｃｈａｒ GET[BUFSIZ];for (pHost = myurl; *pHost != '/' && *pHost != '\0'; ++pHost);// ↓if ( (int)(pHost - myurl) == strlen(myurl) )strcpy(GET, "/");elsestrcpy(GET, pHost);*pHost = '\0';struct hostent *pURL;pURL = gethostbyname(myurl);struct sockaddr_in addr;addr.sin_family = AF_INET;addr.sin_addr.s_addr = *((unsigned long*)pURL->h_addr); // ↑addr.sin_port = htons(80);connect(sockfd,(SOCKADDR *)&addr,sizeof(addr)); // connectingprintf("正在給網絡API（%s）發送請求...\n",url);ｃｈａｒ header[BUFSIZ] = "";strcat(header, "GET ");strcat(header, GET);strcat(header, " HTTP/1.1\r\n");strcat(header, "HOST: ");strcat(header, myurl);strcat(header, "\r\nConnection: Close\r\n\r\n");send(sockfd, header, strlen(header), 0);// sendingprintf("正在處理請求...\n");static ｃｈａｒ text[BUFSIZ*2];while ( recv(sockfd, text, BUFSIZ, 0) > 0); // receivingclosesocket(sockfd);WSACleanup();text[BUFSIZ*2-1] = '\0';if(strlen(text) == 0)printf("text is empty!\n");elseprintf("\n網絡API（%s）返回字符串：\n%s\n",url,text);ｃｈａｒ* subStr = "sysTime1";// 文本處理ｃｈａｒ* str = strstr(text,subStr);if(str == NULL)return NULL;str = str + strlen(subStr) + 3; // "sysTime1":"20220807203344//printf("abc123%s\n",str);ｃｈａｒ *time = (ｃｈａｒ*)malloc(sizeof(ｃｈａｒ)*15);strncpy(time,str,14);time[14] = '\0';printf("\n成功獲得時間:%s\n",time);return time;}/*  * @function : 設置Windows本地時間  * @in: timeStr - 14字節時間字符串(such as 20150415093000)  * @return: 0 - success  *-1 - failure **/int set_local_time(const ｃｈａｒ *timeStr){SYSTEMTIME system_time= {0};ｃｈａｒ year[4 + 1]= {0};ｃｈａｒ month[2 + 1]= {0};ｃｈａｒ day[2 + 1] = {0};ｃｈａｒ hour[2 + 1]= {0};ｃｈａｒ minute[2 + 1]= {0};ｃｈａｒ second[2 + 1]= {0};int index = 0;strncpy(year,timeStr + index, 4);index += 4;strncpy(month,timeStr + index, 2);index += 2;strncpy(day,timeStr + index, 2);index += 2;strncpy(hour,timeStr + index, 2);index += 2;strncpy(minute, timeStr + index, 2);index += 2;strncpy(second, timeStr + index, 2);index += 2;GetLocalTime(&system_time);system_time.wYear= atoi(year);system_time.wMonth= atoi(month);system_time.wDay= atoi(day);system_time.wHour= atoi(hour);system_time.wMinute = atoi(minute);system_time.wSecond = atoi(second);if (0 == SetLocalTime(&system_time))return -1;return 0;}

當然，以上小程序要手動運行才可以同步網絡時間，要自動同步的話，可以通過”計劃任務“自動運行。

以上代碼沒有考慮網絡延遲的問題。在從服務器獲取時間數據時，由于網絡本身的不穩定性，一般會有時間上的延遲（幾秒以內），這樣一來，從服務器接收到的數據總早于真實時間。解決的辦法是設定一個計時器，計算出本機從開始網絡連接到接收完數據所耗費的時間dwDelay，然后加到 dwTime 上進行補償。這樣一來誤差就可以控制在1秒以內。

以下網站返回的時間是豪秒數：

http://api.m.taobao.com/rest/api3.do?api=mtop.common.getTimestamp

頁面顯示：

{"api":"mtop.common.getTimestamp","v":"*","ret":["SUCCESS::接口調用成功"],"data":{"t":"1660091956996"}}

表示從1900.1.1至現在流逝的時間：

#include #include int main (){time_t timer;// typedef long time_tstruct tm y1900 = {0};double seconds;// 定義1900.1.1y1900.tm_hour= 0;y1900.tm_min= 0; y1900.tm_sec= 0;y1900.tm_year= 0; y1900.tm_mon= 0; y1900.tm_mday= 1;time(&timer);/* get current time; same as: timer = time(NULL)*/seconds = difftime(timer,mktime(&y1900));printf ("lapsed %.f seconds since January 1, y1900 to now in the current timezone", seconds);getchar();return 0;}/*output:lapsed 1660093185 seconds since January 1, y1900 to now in the current timezone*/

localtime()可轉換時間格式：

#include #include // struct tm * localtime (const time_t * timer);#if 0struct tm {int tm_sec; /* seconds after the minute - [0,59] */int tm_min; /* minutes after the hour - [0,59] */int tm_hour;/* hours since midnight - [0,23] */int tm_mday;/* day of the month - [1,31] */int tm_mon; /* months since January - [0,11] */int tm_year;/* years since 1900 */int tm_wday;/* days since Sunday - [0,6] */int tm_yday;/* days since January 1 - [0,365] */int tm_isdst;/* daylight savings time flag */};#endifint main (){time_t rawtime;struct tm * timeinfo;time (&rawtime);timeinfo = localtime (&rawtime);printf ("Current local time and date: %s", asctime(timeinfo));getchar();return 0;}/*output:Current local time and date: Wed Aug 10 09:06:33 2022*/

ref

https://www.mmuaa.com/post/3281abd440aeb073.html

https://www.likecs.com/show-306240829.html

－End－