Rebol 编程/for
外观
< Rebol 编程
FOR 'word start end bump body
在一定范围的值上重复一个代码块。
FOR 是一个函数值。
- word -- 用于保存当前值的变量 (类型:词语)
- start -- 起始值 (类型:数字 序列 货币 时间 日期 字符)
- end -- 结束值 (类型:数字 序列 货币 时间 日期 字符)
- bump -- 每次跳过的数量 (类型:数字 货币 时间 字符)
- body -- 要执行的代码块 (类型:代码块)
- 捕获
- 抛出
for: func [ "Repeats a block over a range of values." [catch throw] 'word [word!] "Variable to hold current value" start [number! series! money! time! date! char!] "Starting value" end [number! series! money! time! date! char!] "Ending value" bump [number! money! time! char!] "Amount to skip each time" body [block!] "Block to evaluate" /local result do-body op ][ if (type? start) <> (type? end) [ throw make error! reduce ['script 'expect-arg 'for 'end type? start] ] do-body: func reduce [[throw] word] body op: :greater-or-equal? either series? start [ if not same? head start head end [ throw make error! reduce ['script 'invalid-arg end] ] if (negative? bump) [op: :lesser?] while [op index? end index? start] [ set/any 'result do-body start start: skip start bump ] if (negative? bump) [set/any 'result do-body start] ] [ if (negative? bump) [op: :lesser-or-equal?] while [op end start] [ set/any 'result do-body start start: start + bump ] ] get/any 'result ]