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 putenv()                Create New Environment Variables

 #include   <stdlib.h>                   Required for declarations only

 int        putenv(envstring);
 const char *envstring;                  Environment string definition

    putenv() adds new environment variables or modifies existing ones.
    'envstring' must be a pointer to a string with the form:

                         varname=string

    where 'varname' is the name of the environment variable to be added
    or modified and 'string' is the value of the variable (for example:
    INCLUDE = C:\INCLUDE).  If the specified 'varname' is already set,
    its value is replaced by 'string'.  If it is not already set,
    'envstring' is added to the environment.  If the specified 'varname'
    is already set, and 'string' is empty, 'varname' is deleted.

       Returns:     0, if successful; -1 if an error occurs

         Notes:     Do not free a pointer to an environment variable
                    while the entry is still in use, or the environment
                    variable will point into freed space.  This can
                    effectively happen if you pass a pointer to a local
                    variable to putenv(), and then exit the function in
                    which the local variable was declared.

   -------------------------------- Example ---------------------------------

    The following statements change the PATH to C:\WORK, and then print
    an appropriate message.

           #include <stdlib.h>
           int result;

           main()
           {
               if ((result = putenv("PATH=C:\\WORK")) == 0)
                    printf("path changed to C:\\WORK");
           }