#include <stdlib.h>
#include <string.h>

int set_with_putenv(char *val){
    char myarg[35];
    if (!val || strlen(val)>20){ return -1;}
    return putenv(strcat(strcpy(myarg, "MY_ENV_VAR="), val)); /* 'Use of putenv' warning issued here */
                                                              /* The string pointed to by strcat(strcpy(myarg, "MY_ENV_VAR="), val)
                                                               * has been made part of the environment, but that memory may be overwritten after 
                                                               * control returns from set_with_putenv()
                                                               */ 
}

int set_with_setenv(char *val){
    if (!val || strlen(val)>20){ return -1;}
    return setenv("MY_ENV_VAR", val, 1);                                 /* You can set environment variables with setenv()
                                                                          * to avoid problems with putenv(). */
}