[RESOLVED] _environ

[John E]

I'm working with some code that uses the environment array _environ. It contains a few sections which look like this:-

        char** the_environ = _environ;

        for (size_t i = 0; the_environ[i]; ++i) {
			
                string estring = the_environ[i];
			
                // Do some other stuff
        }

What's happening is that the loop is stepping off the end of the array. At first I thought the solution was obvious. It seemed to me that ++i should really be i++. Unfortunately, even after changing that, I'm still having problems. Let's say there are 16 elements in the environment array. It seems to me that element the_environ[16] isn't guaranteed to be NULL. For example if there were originally 17 entries and then I delete one of them, the_environ[16] seems to get left as a bad pointer.

Is there a better way to get the number of available environment strings?

[2kaud]

See http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx

LPSTR lpszVariable; 
LPCH lpvEnv; 
 
    // Get a pointer to the environment block. 
    lpvEnv = GetEnvironmentStrings();

    // If the returned pointer is NULL, exit.
    if (lpvEnv == NULL)
    {
        printf("GetEnvironmentStrings failed (%d)\n", GetLastError()); 
        return 0;
    }
 
    // Variable strings are separated by NULL byte, and the block is 
    // terminated by a NULL byte. 

    lpszVariable = (LPSTR) lpvEnv;

    while (*lpszVariable)
    {
        printf(TEXT("%s\n"), lpszVariable);
        lpszVariable += lstrlen(lpszVariable) + 1;
    }
    FreeEnvironmentStrings(lpvEnv);

[John E]

Thanks 2kaud. I should have mentioned that I need to keep the solution portable if possible - so something cross-platform would be preferable.

[Edit...] this turned out to be due to a logic problem later in the 'for' loop (it was deleting an environment string - but not taking account of the fact that the number of environment strings was now less).

[VictorN]

Thanks 2kaud. I should have mentioned that I need to keep the solution portable if possible - so something cross-platform would be preferable.

Then you should have posted this question in the non-Visual C++ forum.

[Igor Vartanov]

        for (char** the_environ = _environ; *the_environ; the_environ++) {            
                string estring = *the_environ;            
                // Do some other stuff
        }