Header File 

stdlib.h 

Category 

Process Control Routines 

Prototype 

char *getenv(const char *name); 

wchar_t *_wgetenv(const wchar_t *name); 

Description 

Find or delete an environment variable from the system environment. 

The environment consists of a series of entries that are of the form name=string\0. 

getenv returns the value of a specified variable. name can be either uppercase or lowercase. name must not include the equal sign (=). If the specified environment variable does not exist, getenv returns a NULL pointer. 

To delete the variable from the environment, use getenv("name=").

On success, getenv returns the value associated with name.  

If the specified name is not defined in the environment, getenv returns a NULL pointer. 

Example  

#include <stdio.h>
#include <stdlib.h>
#include <alloc.h>
#include <string.h>
int main(void)
{
   char *path, *ptr;
   int i = 0;
   /* get the current path environment */
   ptr = getenv("PATH");
   /* set up new path */
   path = (char *) malloc(strlen(ptr)+15);
   strcpy(path,"PATH=");
   strcat(path,ptr);
   strcat(path,";c:\\temp");
   /* replace the current path and display current environment */
   putenv(path);
   while (_environ[i])
       printf("%s\n",_environ[i++]);
   return 0;
}

Portability