The Ring programming language version 1.5.1 book - Part 17 of 180
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The document summarizes various control structures in Ring including branching statements like if/else and switch statements. It also covers different looping constructs - while loops, for loops to iterate over a range of numbers, and for-in loops to iterate over elements in a list. Specific examples are given to demonstrate how to use each of these control structures for tasks like menu driven programs, printing number ranges with optional step values, and iterating over list elements.
![CHAPTER
SIXTEEN
VARIABLES
To create a new variable, you just need to determine the variable name & value. The value will determine the variable
type and you can change the value to switch between the types using the same variable name.
Syntax:
<Variable Name> = <Value>
Tip: The operator ‘=’ is used here as an Assignment operator and the same operator can be used in conditions, but
for testing equality of expressions.
Note: The Variable will contains the real value (not a reference). This means that once you change the variable value,
the old value will be removed from memory (even if the variable contains a list or object).
16.1 Dynamic Typing
Ring is a dynamic programming language that uses Dynamic Typing.
x = "Hello" # x is a string
see x + nl
x = 5 # x is a number (int)
see x + nl
x = 1.2 # x is a number (double)
see x + nl
x = [1,2,3,4] # x is a list
see x # print list items
x = date() # x is a string contains date
see x + nl
x = time() # x is a string contains time
see x + nl
x = true # x is a number (logical value = 1)
see x + nl
x = false # x is a number (logical value = 0)
see x + nl
16.2 Deep Copy
We can use the assignment operator ‘=’ to copy variables. We can do that to copy values like strings & numbers. Also,
we can copy complete lists & objects. The assignment operator will do a complete duplication for us. This operation
called Deep Copy
137](https://image.slidesharecdn.com/161ringfayedringdoc1-171205210858/85/The-Ring-programming-language-version-1-5-1-book-Part-17-of-180-3-320.jpg)
![Ring Documentation, Release 1.5.1
list = [1,2,3,"four","five"]
list2 = list
list = []
See list # print the first list - no items to print
See "********" + nl
See list2 # print the second list - contains 5 items
16.3 Weakly Typed
Ring is a weakly typed language, this means that the language can automatically convert between data types (like
string & numbers) when that conversion make sense.
Rules:
<NUMBER> + <STRING> --> <NUMBER>
<STRING> + <NUMBER> --> <STRING>
Note: The same operator ‘+’ can be used as an arithmetic operator or for string concatenation.
Example:
x = 10 # x is a number
y = "20" # y is a string
sum = x + y # sum is a number (y will be converted to a number)
Msg = "Sum = " + sum # Msg is a string (sum will be converted to a string)
see Msg + nl
16.3. Weakly Typed 138](https://image.slidesharecdn.com/161ringfayedringdoc1-171205210858/85/The-Ring-programming-language-version-1-5-1-book-Part-17-of-180-4-320.jpg)
![Ring Documentation, Release 1.5.1
17.4 Bitwise Operators
The next table presents all of the bitwise operators provided by the Ring language. Assume variable X=8 and variable
Y=2 then:
Operator Description Example Result
& Binary AND x & y 0
| Binary OR x | y 10
^ Binary XOR x ^ y 10
~ Binary Ones Complement ~x -9
<< Binary Left Shift x << y 32
>> Binary Right Shift x >> y 2
17.5 Assignment Operators
The next table presents all of the assignment operators provided by the Ring language.
Assume variable X=8 then:
Operator Description Example Result
= Assignment x = 10 x=10
+= Add AND assignment x += 5 x=13
-= Subtract AND assignment x -= 3 x=5
*= Multiply AND assignment x *= 2 x=16
/= Divide AND assignment x /= 3 x=2.67
%= Modulus AND assignment x %= 2 x=0
<<= Left shift AND assignment x <<= 2 x=32
>>= Right shift AND assignment x >>= 2 x=2
&= Bitwise AND assignment x &= 4 x=0
|= Bitwise OR and assignment x |= 3 x=11
^= Bitwise XOR and assignment x ^= 4 x=12
17.6 Misc Operators
Operator Description
:literal using : before identifier mean literal
Start:End create list contains items from start to end
[list items] define list items
list[index] access list item
obj.name using the dot operator to access object members (attributes/methods).
obj {stmts} execute statements with direct access to object attributes & methods
func(para,...) call function using parameters separated by comma
17.7 Operators Precedence
The next table present operators from higher precedence (Evaluated first) to lower precedence.
17.4. Bitwise Operators 140](https://image.slidesharecdn.com/161ringfayedringdoc1-171205210858/85/The-Ring-programming-language-version-1-5-1-book-Part-17-of-180-6-320.jpg)
![Ring Documentation, Release 1.5.1
Operator
. [] () {}
- ~ :Literal [list items]
++ - -
Start:End
* / %
+ -
<< >>
&
| ^
< > <= >=
= !=
not
and or
Assignment = += -= *= /= %=>>= <<= &= ^= |=
Example:
See 3+5*4 # prints 23
17.7. Operators Precedence 141](https://image.slidesharecdn.com/161ringfayedringdoc1-171205210858/85/The-Ring-programming-language-version-1-5-1-book-Part-17-of-180-7-320.jpg)
![Ring Documentation, Release 1.5.1
for identifier=expression to expression [step expression]
Block of statements
next
Example:
# print numbers from 1 to 10
for x = 1 to 10 see x + nl next
Example:
# Dynamic loop
See "Start : " give nStart
See "End : " give nEnd
See "Step : " give nStep
For x = nStart to nEnd Step nStep
see x + nl
Next
Example:
# print even numbers from 0 to 10
for x = 0 to 10 step 2
see x + nl
next
Example:
# print even numbers from 10 to 0
for x = 10 to 0 step -2
see x + nl
next
• For in Loop
Syntax:
for identifier in List/String [step expression]
Block of statements
next
Example:
aList = 1:10 # create list contains numbers from 1 to 10
for x in aList see x + nl next # print numbers from 1 to 10
18.3 Using The Step option with For in
We can use the Step option with For in to skip number of items in each iteration
Example:
aList = 1:10 # create list contains numbers from 1 to 10
# print odd items inside the list
for x in aList step 2
see x + nl
next
18.3. Using The Step option with For in 144](https://image.slidesharecdn.com/161ringfayedringdoc1-171205210858/85/The-Ring-programming-language-version-1-5-1-book-Part-17-of-180-10-320.jpg)
The Ring programming language version 1.5.1 book - Part 17 of 180
- 1. Ring Documentation, Release 1.5.1 15.5 Using Visual Studio IDE Folder : ring/editor/visualstudio Check the ReadMe file for installation instructions. 15.5. Using Visual Studio IDE 135
- 2. Ring Documentation, Release 1.5.1 15.6 Using Emacs Editor Folder : ring/editor/emacs Check the ReadMe file for installation instructions. Screen Shot: 15.6. Using Emacs Editor 136
- 3. CHAPTER SIXTEEN VARIABLES To create a new variable, you just need to determine the variable name & value. The value will determine the variable type and you can change the value to switch between the types using the same variable name. Syntax: <Variable Name> = <Value> Tip: The operator ‘=’ is used here as an Assignment operator and the same operator can be used in conditions, but for testing equality of expressions. Note: The Variable will contains the real value (not a reference). This means that once you change the variable value, the old value will be removed from memory (even if the variable contains a list or object). 16.1 Dynamic Typing Ring is a dynamic programming language that uses Dynamic Typing. x = "Hello" # x is a string see x + nl x = 5 # x is a number (int) see x + nl x = 1.2 # x is a number (double) see x + nl x = [1,2,3,4] # x is a list see x # print list items x = date() # x is a string contains date see x + nl x = time() # x is a string contains time see x + nl x = true # x is a number (logical value = 1) see x + nl x = false # x is a number (logical value = 0) see x + nl 16.2 Deep Copy We can use the assignment operator ‘=’ to copy variables. We can do that to copy values like strings & numbers. Also, we can copy complete lists & objects. The assignment operator will do a complete duplication for us. This operation called Deep Copy 137
- 4. Ring Documentation, Release 1.5.1 list = [1,2,3,"four","five"] list2 = list list = [] See list # print the first list - no items to print See "********" + nl See list2 # print the second list - contains 5 items 16.3 Weakly Typed Ring is a weakly typed language, this means that the language can automatically convert between data types (like string & numbers) when that conversion make sense. Rules: <NUMBER> + <STRING> --> <NUMBER> <STRING> + <NUMBER> --> <STRING> Note: The same operator ‘+’ can be used as an arithmetic operator or for string concatenation. Example: x = 10 # x is a number y = "20" # y is a string sum = x + y # sum is a number (y will be converted to a number) Msg = "Sum = " + sum # Msg is a string (sum will be converted to a string) see Msg + nl 16.3. Weakly Typed 138
- 5. CHAPTER SEVENTEEN OPERATORS In this chapter we will introduce the operators provided by the Ring programming langauge. 17.1 Arithmetic Operators The next table presents all of the arithmetic operators provided by the Ring language. Assume variable X=50 and variable Y=10 then: Operator Description Example Result + Add x+y 60 - Subtract x-y 40 * Multiplies x*y 500 / Divide x/y 5 % Modulus x%y 0 ++ Increment x++ 51 - - Decrement x- - 49 17.2 Relational Operators The next table presents all of the relational operators provided by the Ring language. Assume variable X=50 and variable Y=10 then: Operator Description Example Result = Equal x = y False != Not Equal x != y True > Greater than x > y True < Less than x < y False >= Greater or Equal x >= y True <= Less than or Equal x <= y False 17.3 Logical Operators The next table presents all of the logical operators provided by the Ring language. Assume variable X=True and variable Y=False then: Operator Description Example Result and Logical AND x and y False or Logical OR x or y True not Logical Not not x False 139
- 6. Ring Documentation, Release 1.5.1 17.4 Bitwise Operators The next table presents all of the bitwise operators provided by the Ring language. Assume variable X=8 and variable Y=2 then: Operator Description Example Result & Binary AND x & y 0 | Binary OR x | y 10 ^ Binary XOR x ^ y 10 ~ Binary Ones Complement ~x -9 << Binary Left Shift x << y 32 >> Binary Right Shift x >> y 2 17.5 Assignment Operators The next table presents all of the assignment operators provided by the Ring language. Assume variable X=8 then: Operator Description Example Result = Assignment x = 10 x=10 += Add AND assignment x += 5 x=13 -= Subtract AND assignment x -= 3 x=5 *= Multiply AND assignment x *= 2 x=16 /= Divide AND assignment x /= 3 x=2.67 %= Modulus AND assignment x %= 2 x=0 <<= Left shift AND assignment x <<= 2 x=32 >>= Right shift AND assignment x >>= 2 x=2 &= Bitwise AND assignment x &= 4 x=0 |= Bitwise OR and assignment x |= 3 x=11 ^= Bitwise XOR and assignment x ^= 4 x=12 17.6 Misc Operators Operator Description :literal using : before identifier mean literal Start:End create list contains items from start to end [list items] define list items list[index] access list item obj.name using the dot operator to access object members (attributes/methods). obj {stmts} execute statements with direct access to object attributes & methods func(para,...) call function using parameters separated by comma 17.7 Operators Precedence The next table present operators from higher precedence (Evaluated first) to lower precedence. 17.4. Bitwise Operators 140
- 7. Ring Documentation, Release 1.5.1 Operator . [] () {} - ~ :Literal [list items] ++ - - Start:End * / % + - << >> & | ^ < > <= >= = != not and or Assignment = += -= *= /= %=>>= <<= &= ^= |= Example: See 3+5*4 # prints 23 17.7. Operators Precedence 141
- 8. CHAPTER EIGHTEEN CONTROL STRUCTURES - FIRST STYLE In this chapter we are going to learn about the control structures provided by the Ring programming language. 18.1 Branching • If Statement Syntax: if Expression Block of statements but Expression Block of statements else Block of statements ok Example: see " Main Menu --------- (1) Say Hello (2) About (3) Exit " give nOption if nOption = 1 see "Enter your name : " give name see "Hello " + name + nl but nOption = 2 see "Sample : using if statement" + nl but nOption = 3 bye else see "bad option..." + nl ok • Switch Statement Syntax: switch Expression on Expression Block of statements other Block of statements off 142
- 9. Ring Documentation, Release 1.5.1 Example: See " Main Menu --------- (1) Say Hello (2) About (3) Exit " Give nOption Switch nOption On 1 See "Enter your name : " Give name See "Hello " + name + nl On 2 See "Sample : using switch statement" + nl On 3 Bye Other See "bad option..." + nl Off 18.2 Looping • While Loop Syntax: while Expression Block of statements end Example: While True See " Main Menu --------- (1) Say Hello (2) About (3) Exit " Give nOption Switch nOption On 1 See "Enter your name : " Give name See "Hello " + name + nl On 2 See "Sample : using while loop" + nl On 3 Bye Other See "bad option..." + nl Off End • For Loop Syntax: 18.2. Looping 143
- 10. Ring Documentation, Release 1.5.1 for identifier=expression to expression [step expression] Block of statements next Example: # print numbers from 1 to 10 for x = 1 to 10 see x + nl next Example: # Dynamic loop See "Start : " give nStart See "End : " give nEnd See "Step : " give nStep For x = nStart to nEnd Step nStep see x + nl Next Example: # print even numbers from 0 to 10 for x = 0 to 10 step 2 see x + nl next Example: # print even numbers from 10 to 0 for x = 10 to 0 step -2 see x + nl next • For in Loop Syntax: for identifier in List/String [step expression] Block of statements next Example: aList = 1:10 # create list contains numbers from 1 to 10 for x in aList see x + nl next # print numbers from 1 to 10 18.3 Using The Step option with For in We can use the Step option with For in to skip number of items in each iteration Example: aList = 1:10 # create list contains numbers from 1 to 10 # print odd items inside the list for x in aList step 2 see x + nl next 18.3. Using The Step option with For in 144