.. index:: single: Demo Programs; Introduction ============= Demo Programs ============= In this chapter we will see simple demo programs * Language Shell * Main Menu .. index:: pair: Demo Programs; Language Shell Language Shell ============== We can create simple interactive programming environment using the next program .. code-block:: ring while true see nl + "code:> " give cCode try eval(cCode) catch see cCatchError done end Output: .. code-block:: ring code:> see "hello world" hello world code:> for x = 1 to 10 see x + nl next 1 2 3 4 5 6 7 8 9 10 code:> func test see "Hello from test" + nl code:> test() Hello from test code:> bye .. index:: pair: Demo Programs; Main Menu Main Menu ========= Example: .. code-block:: ring # Demo Program while true see " Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit " give nMenu see nl # we can use Switch-ON-Other-OFF instead of IF-BUT-ELSE-OK Switch nMenu On 1 sayhello() On 2 Sum() On 3 Stars() On 4 see "Enter Number : " give x see "Output : " Try see Fact(number(x)) Catch see "Error in parameters!" + nl Done On "5" return Other see "bad option" + nl Off end func sayhello see "Enter your name ? " give fname see "Hello " + fname + nl func sum see "number 1 : " give num1 see "number 2 : " give num2 see "Sum : " see 0 + num1 + num2 func stars for x = 1 to 10 see space(8) for y = 1 to x see "*" next see nl next func fact x if x = 1 return 1 else return x * fact(x-1) ok func space x y = "" for t=1 to x y += " " next return y Output: .. code-block:: ring Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit 1 Enter your name ? Mahmoud Fayed Hello Mahmoud Fayed Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit 2 number 1 : 3 number 2 : 4 Sum : 7 Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit 3 * ** *** **** ***** ****** ******* ******** ********* ********** Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit 4 Enter Number : 5 Output : 120 Main Menu =========== [1] Say Hello [2] Sum two numbers [3] Stars [4] Fact [5] Exit 5