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Adds new environment variables or modifies the values of existing ones.

#include <stdlib.h>

int putenv (const char *envstring);



Environment-variable table entry definition, which must be a character string of this form:

varname = string


varname The name of the environment variable to be added or modified.
string The variable's value.


putenv operates only on the local process. The process environment is pre-loaded from "global" values which are set in the registry. The registry ...\<nodename>\INTIME.INI\CLIB contains values which are loaded into the environment.

Environment variables customize the environment in which a thread executes. This function affects only the current process' environment; it does not modify the default environment.

If varname is already part of the environment, its value is replaced by string; otherwise, the new variable is placed in the first empty slot in the environment-variable table. If you specify a valid varname and null string, the environment variable is removed.

There is one environment-variable table shared by all threads using the C library. If the table has not been initialized by a previous call to getenv, putenv first calls getenv before proceeding.

Return Values

0 (zero).


Versions Defined in Include Link to
INtime 3.0 intime/rt/include/stdlib.h stdlib.h clib.lib
See Also