Rexx Programming/How to Rexx/control structure

Control structures (also known as control constructs) are constructs used within a program to control the flow of a program based on given conditions. Control structure typically uses conditional branching instructions or loop control statements. Code within control structures is typically arranged into blocks in a similar fashion to control structures written in C.

Conditional Branching
The following example shows a conditional code being used as a conditional branch:

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

Here is a conditional branch with two parts:

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

As mentioned earlier, we can use blocks so that more than one thing can happen if a condition is met (or unmet). 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

Select
Rexx also has a construct for choosing the first true condition from multiple options. 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

Loops
The following example shows a block of code being used in a loop:

do number = 1 to 10 say number end