/* The character conversion functions strlwr() and strupr(). */

#include <stdio.h>
#include <string.h>

main()
{
     char buf[80];

     while (1)
     {
         puts("Enter a line of text, a blank to exit.");
         gets(buf);

         if ( strlen(buf) == 0 )
             break;

         puts(strlwr(buf));
         puts(strupr(buf));
     }
     return(0);
}