Rexx 编程/Rexx 指南/控制结构

控制结构（也称为控制构造）是在程序中用来基于给定条件控制程序流程的构造。控制结构通常使用条件分支指令或循环控制语句。控制结构中的代码通常以类似于 C 语言中控制结构的方式被组织成代码块。

条件分支

以下示例展示了条件代码作为条件分支使用的情况。

if guess = 6 then
  say "Wow! That was a lucky guess."

这是一个包含两个部分的条件分支。

if guess = 6 then
  say "Wow! That was a lucky guess!"
else
  say "Sorry, the number was actually 6."

如前所述，我们可以使用代码块，以便在条件满足（或不满足）时执行多个操作。

if score >= 100 then
 do
  say "Congratulations! You won."
  say "Go ahead and enter your initials below for our high score list."
  initials = LineIn()
 end
else
 do
  say "Let's keep playing!"
  say "What do want your next move to be?"
  next_move = LineIn()
 end

选择

Rexx 还提供了一种构造，用于从多个选项中选择第一个为真的条件。

select
  when age < 3 then
    say "You are a toddler."
  when age < 12 then
    say "You are a child."
  when age < 20 then
    say "You are a teenager."
  when age >= 65 then
    say "You are are a senior."
  when age >= 40 then
    say "You are middle-aged."
  otherwise
    say "You are a young adult."
 end

循环

以下示例展示了代码块在循环中使用的情况。

do number = 1 to 10
  say number
end