- char * option; /* Substring to match. */
- char * help; /* Help information. */
- int (* func) (char * subopt); /* Function to decode sub-option. */
- char * deprecated; /* If non-null, print this message. */
+ const char * option; /* Substring to match. */
+ const char * help; /* Help information. */
+ int (* func) (const char * subopt); /* Function to decode sub-option. */
+ const char * deprecated; /* If non-null, print this message. */