CODEWITHSUNDEEP
c++
performanceuser
performanceuser

Reputation: 2893

how to get system or user temp folder in unix and windows?

I am writing a C++ problem. It need to work on both Windows and Unix OS.

How to get user or system tmp folder on different OS?

Upvotes: 35

Views: 40870

Answers (8)

MelS
MelS

Reputation: 119

According to the docs, the max path is MAX_PATH (260). If the path happens to be 260, the code in the sample above (als plougy) will fail because 261 will be returned. Probably the buffer size should be MAX_PATH + 1.

TCHAR szPath[MAX_PATH + 1];
DWORD result = GetTempPath(MAX_PATH + 1, szPath);
if (result != ERROR_SUCCESS) {
    // check GetLastError()
}

Upvotes: 0

Preet Kukreti
Preet Kukreti

Reputation: 8627

Update: Thanks @RoiDanton, the most up to date answer is std::filesystem::temp_directory_path (C++17)

Try boost::filesystem's temp_directory_path() which internally uses:

  • ISO/IEC 9945 (POSIX): The path supplied by the first environment variable found in the list TMPDIR, TMP, TEMP, TEMPDIR. If none of these are found, "/tmp", or, if macro __ANDROID__ is defined, "/data/local/tmp"

  • Windows: The path reported by the Windows GetTempPath API function.

Interestingly, Window's GetTempPath uses similar logic to the POSIX version: the first environment variable in the list TMP, TEMP, USERPROFILE. If none of these are found, it returns the Windows directory.

The fact that these methods primarily rely on environment variables seems a bit yuck. But thats how it seems to be determined. Seeing as how mundane it really is, you could easily roll your own using cstdlib's getenv function, especially if you want specific order prioritization/requirements or dont want to use another library.

Upvotes: 54

asd plougry
asd plougry

Reputation: 143

None of these examples are really concrete and provide a working example (besides std::filesystem::temp_directory_path) rather they're referring you to microsoft's documentation, here's a working example using "GetTempPath()" (tested on windows 10):

//temp.cpp
#include <iostream>
#include <windows.h>


int main()
{ 
    TCHAR path_buf[MAX_PATH];
    DWORD ret_val = GetTempPath(MAX_PATH, path_buf);
    if ( ret_val > MAX_PATH || (ret_val == 0) )
    {
        std::cout << "GetTempPath failed";
    } else {
        std::cout << path_buf;
    }
}

outputs:

C:\>temp.exe
C:\Users\username\AppData\Local\Temp\

Upvotes: -1

Deadlock
Deadlock

Reputation: 4519

On Windows: Use GetTempPath() to retrieve the path of the directory designated for temporary files.

wstring TempPath;
wchar_t wcharPath[MAX_PATH];
if (GetTempPathW(MAX_PATH, wcharPath))
  TempPath = wcharPath;

Upvotes: -1

ASten
ASten

Reputation: 814

If you get an access to main() function code, may be better is to put necessary folder names through the main()'s **argv and use an OS-dependend batch launcher. For example, for UNIX

bash a_launcher.sh

where a_launcher.sh is like

./a.out /tmp

Upvotes: -1

FailedDev
FailedDev

Reputation: 26940

Handy function : 

std::string getEnvVar( std::string const & key )
{
    char * val = getenv( key.c_str() );
    return val == NULL ? std::string("") : std::string(val);
}

I guess TEMP or something could be passed as an argument? Depending on the OS of course. getenv is part of stdlib so this should also be portable.

Upvotes: -1

A.H
A.H

Reputation: 1025

if you use QT(Core) you can try QString QDir::tempPath() , or use it's implementation in your code (QT is open, so, check how they do).

The doc say : On Unix/Linux systems this is usually /tmp; on Windows this is usually the path in the TEMP or TMP environment variable.

Upvotes: 4

Jonathan Leffler
Jonathan Leffler

Reputation: 755094

Use the $TMPDIR environment variable, according to POSIX.

char const *folder = getenv("TMPDIR");
if (folder == 0)
    folder = "/tmp";

Upvotes: 10

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