INFO: Storage of Environment Variables

• The C Run-Time (CRT), included with:
  • Microsoft C for MS-DOS, versions 5.1, 6.0, 6.0a, 6.0ax
  • Microsoft C for OS/2, versions 5.1, 6.0, 6.0a
  • Microsoft C/C++ for MS-DOS, version 7.0
  • Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5
  • Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 5.0, 6.0

SUMMARY

The environ variable is an array of pointers to the strings that constitute the process's environment. The C startup code takes the environment information and initializes the environ variable to point to the environment table. The function getenv() uses the environ variable to access the environment table. environ can be used to obtain the environment table address directly.

The following program prints out the address of the beginning of the environment table and the PATH environment variable:

Sample Code

#include <stdlib.h>
#include <stdio.h>

char *path;

void main (void)
{
  path = getenv( "PATH" );
  printf( "path: %s\nenviron: %x\n", path, environ );
} 

Additional query words:

Keywords : kbcode kbCRT kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600
Version : MS-DOS:5.1,6.0,6.00a,6.00ax,7.0; OS/2:5.1,6.0,6.00a; WINDOWS:1.0,1.5; WINDOWS NT:1.0,2.0,4.0,5.0
Platform : MS-DOS NT OS/2 WINDOWS
Issue type : kbinfo