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#include <stdio.h>
int key_to_index(key)
char key;
{
if ( key >= '0' && key <= '9' )
return (int)(key - '0');
else if ( key >= 'a' && key <= 'c' )
return (int)(key - 'a') + 10;
else if ( key >= 'e' && key <= 'f' )
return (int)(key - 'e') + 13;
else return -100;
}
char index_to_key(index)
int index;
{
if ( index >= 0 && index <= 9 )
return (char)(index + '0');
else if ( index >= 10 && index <= 12 )
return (char)(index - 10 + 'a');
else if ( index >= 13 && index <= 14 )
return (int)(index - 13 + 'e');
else
/* huh? */
return '?';
}
int main()
{
int i;
for ( i=0; i<16; i++ )
{
printf( "%d ==> %c:%d\n",
i, index_to_key(i), key_to_index(index_to_key(i)) );
}
}
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