Delphi顺序类成员函数
1. succ(x) : 返回有序值的后继数,
如: succ('e') --> 'f'; succ(3) --> 4
如: Type Colors = (RED,BLUE,GREEN);
succ(BLUE)_ --> GREEN;
2. pred(x): 返回有序值的前继数
如: pred('e') --> 'd'; pred(3) --> 2
如: Type Colors = (RED,BLUE,GREEN);
pred(BLUE)_ --> RED;