当我使用模板时，未在此范围GCC Linux环境中声明strerror_s，strcpy_s，localtime_s，sprintf_s？

Posted 2021-03-29

我编写了一个跨平台代码，给出了当前日期（mm / dd / yy）和时间（hh / mm / ss）和完整日期（yyyymmdd），此代码适用于Windows（MSVS2015）但不适用于Linux（GCC） 4.8.5）。

我的代码是

#include <iostream> 
#ifdef WIN32
#include <windows.h>
#else
#include <cerrno>
#endif

#ifdef WIN32
#include <direct.h>
#include <io.h>
#else
#include <dirent.h>
#include <stdio.h>
#include <unistd.h>
#endif
#include <ctime>
#include <bitset>
#include <cstdlib>  /*atol*/
#include <iomanip>
#include <stdexcept>
#include <cstring>
#include <cstdio>
#include <fstream>
using namespace std;

template <size_t size>
void GetNowDateTime(char(&c_date)[size], char(&c_time)[size])
{
   time_t t;
   struct tm now;
   strcpy_s(c_date, "00/00/00");
   strcpy_s(c_time, "00:00:00");
   time(&t);
  if (localtime_s(&now, &t) != 0) return;
 char temp[3];
 sprintf_s(temp, "%.2d", now.tm_mon + 1);
 memcpy(c_date, temp, 2);
 sprintf_s(temp, "%.2d", now.tm_mday);
 memcpy(c_date + 3, temp, 2);
 sprintf_s(temp, "%.2d", now.tm_year - 100);
 memcpy(c_date + 6, temp, 2);
 sprintf_s(temp, "%.2d", now.tm_hour);
 memcpy(c_time, temp, 2);
 sprintf_s(temp, "%.2d", now.tm_min);
 memcpy(c_time + 3, temp, 2);
 sprintf_s(temp, "%.2d", now.tm_sec);
 memcpy(c_time + 6, temp, 2);
 }

  int GetToday(void)
  {
    time_t t;
    struct tm now;
    time(&t);
    if (localtime_s(&now, &t) != 0) return 0;
    return (now.tm_year + 1900) * 10000 + (now.tm_mon + 1) * 100 + now.tm_mday;
  }

 bool OpenOuputFile(ofstream& outputFile)
 {

  char buf[1024];

 #ifdef WIN32
   strcpy_s(buf, "C:\Myfolder\output.txt");
  #else
    strcpy_s(buf, "/home/myfolder/output.txt");
    #endif
    outputFile.open(buf, ios::out);

    if (!outputFile)
    {
    char szErrorMsg[1024];
    strerror_s(szErrorMsg, errno);
    cout << "Unable to open input file. " << buf << " Error:" << szErrorMsg << endl;
    return 0;
}
return 1;
}

//这是我的主要功能

int main()
{
char today[9];
char time[9];
ofstream outputFile;
GetNowDateTime(today, time);
int yyyymmdd = GetToday();
if (OpenOuputFile(outputFile))
{
    outputFile << "GetNowDateTime functions given is:-	" << today << "	" << time << endl;
    outputFile << "GetToday Function given is:-	" << yyyymmdd << endl;
   }
   else
    cout << "No output file written" << endl;
return 0;
} 

Linux中的错误是

TimeDate.cpp: In function ‘void GetNowDateTime(char (&)[size], char (&)[size])’:

TimeDate.cpp:34:26: error: there are no arguments to ‘localtime_s’ that depend on a template parameter, so a declaration of ‘localtime_s’ must be available [-fpermissive]
  if (localtime_s(&now, &t) != 0) return;
TimeDate.cpp:36:40: error: there are no arguments to ‘sprintf_s’ that depend on a template parameter, so a declaration of ‘sprintf_s’ must be available [-fpermissive]
imeDate.cpp: In function ‘int GetToday()’:
TimeDate.cpp:55:26: error: ‘localtime_s’ was not declared in this scope
if (localtime_s(&now, &t) != 0) return 0;
TimeDate.cpp:74:31: error: ‘strerror_s’ was not declared in this scope
strerror_s(szErrorMsg, errno);
TimeDate.cpp:31:29: error: ‘strcpy_s’ was not declared in this scope
strcpy_s(c_date, "00/00/00");

该程序在（windows）visual studio 2015和（Linux）GCC 4.8.5上运行。

我包含了所有必需的标题，但它在Linux中编译时显示错误。

为什么在Linux上出现上述错误，请告诉我。

答案

strcpy_s和朋友是微软对c的扩展，它们在C11中被标准化。 GCC 4.8.5不支持它们，新版本可能不支持When will the safe string functions of C11 be part of glibc?

另一答案

sprintf_s和其他_s函数不是标准C ++的一部分。您的程序将仅限于具有非标准扩展功能的编译器。