Compilare: user.c: In function ‘var_new’: user.c:35:5: warning: implicit declaration of function ‘strdup’ [-Wimplicit-function-declaration] var->key = strdup(key); ^ user.c:35:14: warning: assignment makes pointer from integer without a cast [enabled by default] var->key = strdup(key); ^ user.c:36:16: warning: assignment makes pointer from integer without a cast [enabled by default] var->value = strdup(value); ^