This document provides examples and documentation for various Ring programming language functions related to input/output, file handling, debugging, and creating demo programs. It describes functions for getting command line arguments, the active source file name, changing directories, and more. It also covers try/catch error handling, the eval() function for executing code as a string, and assert() for validating conditions. Finally, it presents two demo programs - an interactive shell and a menu-driven program - to demonstrate basic Ring concepts.

1. Ring Documentation, Release 1.5.2
IsLinux() --> 0
IsFreeBSD() --> 0
IsAndroid() --> 0
32.12 Windowsnl() Function
We can get the windows new line string using the Windowsnl() function.
Syntax:
WindowsNL() ---> Returns a string contains CR+LF = CHAR(13) + CHAR(10)
Example:
cStr = read("input.txt")
if iswindows()
cStr = substr(cStr,windowsnl(),nl)
ok
aList = str2list(cStr)
# to do - list items processing using "for in"
cStr = list2str(aList)
if iswindows()
cStr = substr(cStr,nl,windowsnl())
ok
write("ouput.txt",cStr)
32.13 Get Command Line Arguments
We can get the command line arguments passed to the ring script using the sysargv variable.
The sysargv variable is a list contains the command line parameters.
Example
see copy("=",30) + nl
see "Command Line Parameters" + nl
see "Size : " + len(sysargv) + nl
see sysargv
see copy("=",30) + nl
if len(sysargv) < 4 return ok
nStart = sysargv[3]
nEnd = sysargv[4]
for x = nStart to nEnd
see x + nl
next
Output
b:mahmoudappsring>ring testssyspara.ring 1 10
==============================
Command Line Parameters
32.12. Windowsnl() Function 225

2. Ring Documentation, Release 1.5.2
Size : 4
ring
testssyspara.ring
1
10
==============================
1
2
3
4
5
6
7
8
9
10
32.14 Get Active Source File Name
We can get the active source file name (*.ring) using the filename() function
Syntax:
filename() ---> String contains the active source file name.
Example:
see "Active Source File Name : " + filename() + nl
Output:
Active Source File Name : testsfilename.ring
Example:
if sysargv[2] = filename()
see "I'm the main program file!" + nl
# we can run tests here!
else
see "I'm a sub file in a program" + nl
ok
32.15 PrevFileName() Function
Using the PrevFileName() function we can get the previous active source file name.
The previous file would be the file of the caller function, Or the file of the function that we called before calling
PrevFileName().
Syntax:
prevfilename() ---> String contains the previous source file name.
Example:
The next function in stdlib.ring uses the PrevFileName() to know if the file of the caller function is the main source
file of the program or not.
32.14. Get Active Source File Name 226

3. Ring Documentation, Release 1.5.2
Func IsMainSourceFile
if PrevFileName() = sysargv[2]
return true
ok
return false
32.16 CurrentDir() Function
Return the path of the current directory
Syntax:
CurrenDir() ---> String contains the path of the currect directory
32.17 ExeFileName() Function
Return the Ring executable file name
Syntax:
exefilename() ---> String contains the Ring executable file name
32.18 ChDir() Function
Change the current directory
Syntax:
ChDir(cNewPath)
32.19 ExeFolder() Function
Return the Ring executable file path
Syntax:
exefolder() ---> String contains the Ring executable path
32.20 Version() Function
Return the Ring version
Syntax:
version() ---> String contains the Ring version
Output:
32.16. CurrentDir() Function 227

4. Ring Documentation, Release 1.5.2
1.5.2
32.21 Shutdown() Function
Close the application
Syntax:
shutdown(nStatus) ---> Close the application
32.21. Shutdown() Function 228

5. CHAPTER
THIRTYTHREE
EVAL() AND DEBUGGING
In this chapter we are going to learn about
• Error Handling using Try/Catch/Done
• Eval() function
• Raise() function
• Assert() function
33.1 Try/Catch/Done
Syntax:
Try
Statements...
Catch
Statements...
Done
The statements in the Try block will be executed, if any error happens then the statements in the catch block will be
executed.
Inside the catch block we can use the variable cCatchError to get the error message
Example:
Try
see 5/0
Catch
see "Catch!" + nl + cCatchError
Done
Output:
Catch!
Error (R1) : Cann't divide by zero !
33.2 Eval() Function
We can execute code during the runtime from string using the Eval() function
Syntax:
229

6. Ring Documentation, Release 1.5.2
Eval(cCode)
Example:
Eval("nOutput = 5+2*5 " )
See "5+2*5 = " + nOutput + nl
Eval("for x = 1 to 10 see x + nl next")
Eval("func test see 'message from test!' ")
test()
Output:
5+2*5 = 15
1
2
3
4
5
6
7
8
9
10
message from test!
33.3 Raise() Function
We can raise an exception using the Raise() function
Syntax:
Raise(cErrorMessage)
The function will display the error message then end the execution of the program.
We can use Try/Catch/Done to avoid exceptions generated by raise() function.
Example:
nMode = 10
if nMode < 0 or nMode > 5
raise("Error : nMode not in the range 1:4")
ok
Output:
Line 4 Error : nMode not in the range 1:4
In raise in file testsraise.ring
Example:
try
testmode(6)
catch
see "avoid raise!"
done
testmode(-1)
33.3. Raise() Function 230

7. Ring Documentation, Release 1.5.2
func testmode nMode
if nMode < 0 or nMode > 5
raise("Error : nMode not in the range 1:4")
ok
Output:
avoid raise!
Line 12 Error : nMode not in the range 1:4
In raise In function testmode() in file testsraise2.ring
called from line 7 in file testsraise2.ring
33.4 Assert() Function
We can use the Assert() function to test conditions before executing the code
If the test fail the program will be terminated with an error message contains the assert condition.
Syntax:
Assert( condition )
Example:
x = 10
assert( x = 10)
assert( x = 100 )
Output:
Line 3 Assertion Failed!
In assert in file testsassert.ring
33.4. Assert() Function 231

8. CHAPTER
THIRTYFOUR
DEMO PROGRAMS
In this chapter we will see simple demo programs
• Language Shell
• Main Menu
34.1 Language Shell
We can create simple interactive programming environment using the next program
while true
see nl + "code:> "
give cCode
try
eval(cCode)
catch
see cCatchError
done
end
Output:
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
232

9. Ring Documentation, Release 1.5.2
34.2 Main Menu
Example:
# 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 = 0 return 1 else return x * fact(x-1) ok
34.2. Main Menu 233

10. Ring Documentation, Release 1.5.2
func space x y = "" for t=1 to x y += " " next return y
Output:
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
34.2. Main Menu 234