Question

How do I get the list of all environment variables in C and/or C++?

I know that getenv can be used to read an environment variable, but how do I list them all?

Answer 1

The environment variables are made available to main() as the envp argument – a null terminated array of strings:

int main(int argc, char **argv, char **envp)
{
  for (char **env = envp; *env != 0; env++)
  {
    char *thisEnv = *env;
    printf("%s\n", thisEnv);    
  }
  return 0;
}