从VC6迁移到VS2005 - LocalTime

    我们在编程时，会使用比较多的日期、时间等值；其中time、localtime是经常使用的！

    time函数声明：

time_t time(
   time_t *timer 
);

    locatime结构声明：

struct tm *localtime(
   const time_t *timer 
);

   大部分我们需要输出一个像：xxxx-xx-xx格式的日期

   下面的程序在VC6中调试通过：

/* 
 *  Gets the local system time 
 * 
 *  Created on: 2011-12-24 
 *  Author: xiaobin 
 */
char *getLocalMachineTime()
{
	struct tm *myTime;
	time_t long_time;
	time(&long_time);
	myTime = localtime(&long_time);

	char *result = NULL;
	result = (char *)malloc(1);

	int iYear = myTime->tm_year;
	iYear += 1900;

	char *myYear = (char *)malloc(5);
	myYear = _itoa(iYear, myYear, 10);

	strcpy(result, myYear);
	strncat(result, "-", 1);

	int iMonth = myTime->tm_mon;
	iMonth += 1;

	char *myMonth = (char *)malloc(3);
	if(iMonth < 10) {
		strcpy(myMonth, "0");
	} 
	_itoa(iMonth, myMonth, 10);

	strncat(result, myMonth, sizeof(myMonth));
	strncat(result, "-", 1);

	int iDay = myTime->tm_mday;

	char *myDay = (char *)malloc(3);
	if(iDay < 10) {
		strcpy(myDay, "0");
	} 
	_itoa(iDay, myDay, 10);

	strncat(result, myDay, sizeof(myDay));

	return result;
}

    输出：

2013-09-09

    上一篇博文 《从VC6迁移到VS2005 - METHOD》，我们知道要使用安全函数“*_s”。

    需要更改的函数主要为：localtime->localtime_s、_itoa->_itoa_s、strcpy->strcpy_s、strncat->strncat_s

    localtime_s函数声明：

errno_t localtime_s(
   struct tm* _tm,
   const time_t *time 
);

    _itoa_s函数声明：

errno_t _itoa_s(
   int value,
   char *buffer,
   size_t sizeInCharacters,
   int radix 
);

    其中的radix参数为进制数：2，8，10，16进制等等

    strcpy_s函数声明：

errno_t strcpy_s(
   char *strDestination,
   size_t numberOfElements,
   const char *strSource 
);

    strncat_s函数声明：

errno_t strncat_s(
   char *strDest,
   size_t numberOfElements,
   const char *strSource,
   size_t count
);

    以下程序在VS2005以上版本编译通过：

/* 
 *  Gets the local system time 
 * 
 *  Created on: 2011-12-24 
 *  Author: xiaobin 
 */
char *getLocalMachineTime()
{
	struct tm myTime;
	time_t long_time;
	time(&long_time);
	localtime_s(&myTime, &long_time);

	char result[12];

	int iYear = myTime.tm_year;
	iYear += 1900;

	char chYear[5];
	_itoa_s(iYear, chYear, 5, 10);

	strcpy_s(result, chYear);
	strncat_s(result, "-", 1);

	int iMonth = myTime.tm_mon;
	iMonth += 1;

	char chZero[] = "0";

	char chMonth[3];
	_itoa_s(iMonth, chMonth, 3, 10);
	if(iMonth < 10) {
		strncat_s(result, chZero, 2);
	} 

	strncat_s(result, chMonth, 2);
	strncat_s(result, "-", 1);

	int iDay = myTime.tm_mday;

	char chDay[3];
	_itoa_s(iDay, chDay, 3, 10);
	if(iDay < 10) {
		strncat_s(result, chZero, 2);
	}

	strncat_s(result, chDay, 3);

	return result;
}

    程序测试：

// prjLocalDateTime.cpp : Defines the entry point for the console application.
//
/* 
 *  prjLocalDateTime.cpp 
 * 
 *  Created on: 2011-12-24 
 *  Author: xiaobin 
 */

#include "stdafx.h"
#include <comdef.h>
#include "time.h"
#include <stdlib.h>


char *getLocalMachineTime();

int _tmain(int argc, _TCHAR* argv[])
{
	char dateChar[12];
	char *temp = getLocalMachineTime();
	strcpy(dateChar, temp);
	for(int i=0; i<12; i++){
		printf("%c", dateChar[i]);
	}
	return 0;
}