#include <ctype.h> char * to_lower(string) /* convert all uppercase chars to lower. returns arg */ char *string; { register char *str = string; while(*str) { if(isupper(*str)) *str = tolower(*str); str++; } return( string ); } char * to_upper(string) /* convert all lowercase chars to upper. returns arg */ char *string; { register char *str = string; while(*str) { if(islower(*str)) *str = toupper(*str); str++; } return( string ); }