The Ring programming language version 1.9 book - Part 34 of 210
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This document provides documentation on Ring programming language functions for working with directories, files, versions and shutting down applications. It includes functions such as CurrentDir(), ExeFileName(), ChDir(), ExeFolder(), Version() and Shutdown(). It also covers error handling using Try/Catch/Done, executing code dynamically using Eval(), raising exceptions with Raise() and testing conditions with Assert(). Finally, it presents two simple demo programs - a language shell and a main menu application.
![Ring Documentation, Release 1.9
Func IsMainSourceFile
if PrevFileName() = sysargv[2]
return true
ok
return false
36.16 CurrentDir() Function
Return the path of the current directory
Syntax:
CurrenDir() ---> String contains the path of the currect directory
36.17 ExeFileName() Function
Return the Ring executable file name
Syntax:
exefilename() ---> String contains the Ring executable file name
36.18 ChDir() Function
Change the current directory
Syntax:
ChDir(cNewPath)
36.19 ExeFolder() Function
Return the Ring executable file path
Syntax:
exefolder() ---> String contains the Ring executable path
36.20 Version() Function
Return the Ring version
Syntax:
version() ---> String contains the Ring version
Output:
36.16. CurrentDir() Function 299](https://image.slidesharecdn.com/331ring-181106093622/85/The-Ring-programming-language-version-1-9-book-Part-34-of-210-1-320.jpg)
![Ring Documentation, Release 1.9
38.2 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
38.2. Main Menu 305](https://image.slidesharecdn.com/331ring-181106093622/85/The-Ring-programming-language-version-1-9-book-Part-34-of-210-7-320.jpg)
![Ring Documentation, Release 1.9
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
38.2. Main Menu 306](https://image.slidesharecdn.com/331ring-181106093622/85/The-Ring-programming-language-version-1-9-book-Part-34-of-210-8-320.jpg)
![Ring Documentation, Release 1.9
[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
38.2. Main Menu 307](https://image.slidesharecdn.com/331ring-181106093622/85/The-Ring-programming-language-version-1-9-book-Part-34-of-210-9-320.jpg)
The Ring programming language version 1.9 book - Part 34 of 210
- 1. Ring Documentation, Release 1.9 Func IsMainSourceFile if PrevFileName() = sysargv[2] return true ok return false 36.16 CurrentDir() Function Return the path of the current directory Syntax: CurrenDir() ---> String contains the path of the currect directory 36.17 ExeFileName() Function Return the Ring executable file name Syntax: exefilename() ---> String contains the Ring executable file name 36.18 ChDir() Function Change the current directory Syntax: ChDir(cNewPath) 36.19 ExeFolder() Function Return the Ring executable file path Syntax: exefolder() ---> String contains the Ring executable path 36.20 Version() Function Return the Ring version Syntax: version() ---> String contains the Ring version Output: 36.16. CurrentDir() Function 299
- 2. Ring Documentation, Release 1.9 1.9 36.21 Shutdown() Function Close the application Syntax: shutdown(nStatus) ---> Close the application 36.21. Shutdown() Function 300
- 3. CHAPTER THIRTYSEVEN EVAL() AND DEBUGGING In this chapter we are going to learn about • Error Handling using Try/Catch/Done • Eval() function • Raise() function • Assert() function 37.1 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 ! 37.2 Eval() Function We can execute code during the runtime from string using the Eval() function Syntax: 301
- 4. Ring Documentation, Release 1.9 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! We can use the Return command to return a value Example: see Eval("return 5*5") Output: 25 37.3 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 37.3. Raise() Function 302
- 5. Ring Documentation, Release 1.9 Example: try testmode(6) catch see "avoid raise!" done testmode(-1) 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 37.4 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 37.4. Assert() Function 303
- 6. CHAPTER THIRTYEIGHT DEMO PROGRAMS In this chapter we will see simple demo programs • Language Shell • Main Menu 38.1 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 304
- 7. Ring Documentation, Release 1.9 38.2 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 38.2. Main Menu 305
- 8. Ring Documentation, Release 1.9 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 38.2. Main Menu 306
- 9. Ring Documentation, Release 1.9 [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 38.2. Main Menu 307
- 10. CHAPTER THIRTYNINE ODBC FUNCTIONS This chapter contains the ODBC functions provided by the Ring programming language. • odbc_init() • odbc_drivers() • odbc_datasources() • odbc_close() • odbc_connect() • odbc_disconnect() • odbc_execute() • odbc_colcount() • odbc_fetch() • odbc_getdata() • odbc_tables() • odbc_columns() • odbc_autocommit() • odbc_commit() • odbc_rollback() Before using the next function load the odbclib.ring library load "odbclib.ring" # Use ODBC functions 39.1 odbc_init() Function We can create ODBC Handle using the odbc_init() function Syntax: odbc_init() ---> ODBC Handle 308