The Ring programming language version 1.3 book - Part 14 of 88
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The document provides information on string manipulation functions in Ring including reversing lists, inserting items into lists, accessing nested lists, copying lists, and passing lists to functions. Key functions covered are reverse(), insert(), accessing nested list items, assignment operator for copying lists, and passing lists by reference to modify them in called functions.
![Ring Documentation, Release 1.3
Reverse(List) ---> Reversed List
Example:
aList = [10,20,30,40,50]
aList = reverse(aList)
see aList # print 50 40 30 20 10
22.10 Insert Items
To insert an item in the list we can use the insert() function.
Syntax:
Insert(List,Index,Item)
The inserted item will be AFTER the Index
Example:
aList = ["A","B","D","E"]
insert(aList,2,"C") # Inserts AFTER Index 2, "C" into Position 3
see aList # print A B C D E
22.11 Nested Lists
The list may contain other lists
Example:
aList = [ 1 , [10,20,30] , 5 , [100,1000,5000] ]
aList2 = [
"one","two",
[3,4],
[20,30], ["three",
"four",
"five",[100,200,300]
]
]
see aList[2] # print 10 20 30
see aList[4][3] + nl # print 5000
see aList2[5][2] + nl # print four
see aList2[5][4][3] # print 300
22.12 Copy Lists
We can copy lists (including nested lists) using the Assignment operator.
Example:
22.10. Insert Items 108](https://image.slidesharecdn.com/131ringring-170612194223/85/The-Ring-programming-language-version-1-3-book-Part-14-of-88-1-320.jpg)
![Ring Documentation, Release 1.3
aList = [
"one","two",
[3,4],
[20,30], ["three",
"four",
"five",[100,200,300]
]
]
aList2 = aList # Copy aList to aList2
aList2[5] = "other" # modify item number five
see aList2[5] + nl # print other
see aList[5] # print three four five 100 200 300
22.13 First-class lists
Lists are first-class citizens where we can store lists in variables, pass lists to functions, and return lists from functions.
Example:
aList = duplicate( [1,2,3,4,5] )
see aList[10] + nl # print 5
see mylist() # print 10 20 30 40 50
func duplicate list
nMax = len(list)
for x = 1 to nMax
list + list[x]
next
return list
func mylist return [10,20,30,40,50]
22.14 Using Lists during definition
We can use the list items while we are defining the list for the first time.
Example:
aList = [ [1,2,3,4,5] , aList[1] , aList[1] ]
see aList # print 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
22.15 Passing Lists to Functions
Lists are passed to functions by reference, This means that the called function will work on the same list and can
modify it.
Example:
func main
aList = [1,2,3,4,5] # create list, local in function main
22.13. First-class lists 109](https://image.slidesharecdn.com/131ringring-170612194223/85/The-Ring-programming-language-version-1-3-book-Part-14-of-88-2-320.jpg)
![Ring Documentation, Release 1.3
myfunc(aList) # call function, pass list by reference
see aList # print 1 2 3 4 5 6 7 8 9 10
func myfunc list
list + [6,7,8,9,10]
22.16 Access List Items by String Index
Instead of using numbers to determine the item index when we get item value or set item value, We can access items
using string index if the item is a list contains two items and the first item is a string.
Example:
aList = [ ["one",1] , ["two",2] , ["three",3] ]
see aList["one"] + nl +
aList["two"] + nl +
aList["three"] # print 1 2 3
This type of lists can be defined in a better syntax using the : and = operators.
Example:
aList = [ :one = 1 , :two = 2 , :three = 3 ]
see aList["one"] + nl +
aList["two"] + nl +
aList["three"] + nl # print 1 2 3
see aList[1] # print one 1
Tip: using : before identifier (one word) means literal
Note: using = inside list definition create a list of two items where the first item is the left side and the second item is
the right side.
We can add new items to the list using the string index
Example:
aList = []
aList["Egypt"] = "Cairo"
aList["KSA"] = "Riyadh"
see aList["Egypt"] + nl + # print Cairo
aList["KSA"] + nl # print Riyadh
22.17 Passing Parameters Using List
This type of lists is very good for passing parameters to functions Where the order of parameters will not be important
(we can change the order).
Also some parameters maybe optional.
Example:
22.16. Access List Items by String Index 110](https://image.slidesharecdn.com/131ringring-170612194223/85/The-Ring-programming-language-version-1-3-book-Part-14-of-88-3-320.jpg)
![Ring Documentation, Release 1.3
myconnect ( [ :server = "myserver.com" , :port = 80 ,
:username = "mahmoud" , :password = "password" ] )
func myconnect mypara
# print connection details
see "User Name : " + mypara[:username] + nl +
"Password : " + mypara[:password] + nl +
"Server : " + mypara[:server] + nl +
"Port : " + mypara[:port]
22.18 Swap Items
We can swap the list items using the Swap() function.
Example:
aList = [:one,:two,:four,:three]
see aList
see copy("*",50) + nl
swap(aList,3,4)
see aList
Output
one
two
four
three
**************************************************
one
two
three
four
22.18. Swap Items 111](https://image.slidesharecdn.com/131ringring-170612194223/85/The-Ring-programming-language-version-1-3-book-Part-14-of-88-4-320.jpg)
![Ring Documentation, Release 1.3
23.4 Access String Letters
We can access a letter inside a string by the letter index
Syntax:
string[index] ---> get string letter
string[index] = letter # set string letter
Example:
# print user name letter by letter (each letter in new line)
See "Hello, Enter your name : " give cName
for x = 1 to len(cName)
see nl + cName[x]
next
We can use for in to get string letters.
Example:
# print user name letter by letter (each letter in new line)
See "Hello, Enter your name : " give cName
for x in cName
see nl + x
next
We can modify the string letters
Example:
# convert the first letter to UPPER case
See "Enter your name : " give cName
cName[1] = upper(cName[1])
see "Hello " + cName
23.5 Left() Function
We can get a specified number of characters from a string using the Left() function.
The starting position is 1.
Syntax:
Left(string,count)
Example:
see left("Hello World!",5) # print Hello
23.6 Right() Function
We can get a specified number of characters from a string using the Right() function.
23.4. Access String Letters 113](https://image.slidesharecdn.com/131ringring-170612194223/85/The-Ring-programming-language-version-1-3-book-Part-14-of-88-6-320.jpg)
The Ring programming language version 1.3 book - Part 14 of 88
- 1. Ring Documentation, Release 1.3 Reverse(List) ---> Reversed List Example: aList = [10,20,30,40,50] aList = reverse(aList) see aList # print 50 40 30 20 10 22.10 Insert Items To insert an item in the list we can use the insert() function. Syntax: Insert(List,Index,Item) The inserted item will be AFTER the Index Example: aList = ["A","B","D","E"] insert(aList,2,"C") # Inserts AFTER Index 2, "C" into Position 3 see aList # print A B C D E 22.11 Nested Lists The list may contain other lists Example: aList = [ 1 , [10,20,30] , 5 , [100,1000,5000] ] aList2 = [ "one","two", [3,4], [20,30], ["three", "four", "five",[100,200,300] ] ] see aList[2] # print 10 20 30 see aList[4][3] + nl # print 5000 see aList2[5][2] + nl # print four see aList2[5][4][3] # print 300 22.12 Copy Lists We can copy lists (including nested lists) using the Assignment operator. Example: 22.10. Insert Items 108
- 2. Ring Documentation, Release 1.3 aList = [ "one","two", [3,4], [20,30], ["three", "four", "five",[100,200,300] ] ] aList2 = aList # Copy aList to aList2 aList2[5] = "other" # modify item number five see aList2[5] + nl # print other see aList[5] # print three four five 100 200 300 22.13 First-class lists Lists are first-class citizens where we can store lists in variables, pass lists to functions, and return lists from functions. Example: aList = duplicate( [1,2,3,4,5] ) see aList[10] + nl # print 5 see mylist() # print 10 20 30 40 50 func duplicate list nMax = len(list) for x = 1 to nMax list + list[x] next return list func mylist return [10,20,30,40,50] 22.14 Using Lists during definition We can use the list items while we are defining the list for the first time. Example: aList = [ [1,2,3,4,5] , aList[1] , aList[1] ] see aList # print 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 22.15 Passing Lists to Functions Lists are passed to functions by reference, This means that the called function will work on the same list and can modify it. Example: func main aList = [1,2,3,4,5] # create list, local in function main 22.13. First-class lists 109
- 3. Ring Documentation, Release 1.3 myfunc(aList) # call function, pass list by reference see aList # print 1 2 3 4 5 6 7 8 9 10 func myfunc list list + [6,7,8,9,10] 22.16 Access List Items by String Index Instead of using numbers to determine the item index when we get item value or set item value, We can access items using string index if the item is a list contains two items and the first item is a string. Example: aList = [ ["one",1] , ["two",2] , ["three",3] ] see aList["one"] + nl + aList["two"] + nl + aList["three"] # print 1 2 3 This type of lists can be defined in a better syntax using the : and = operators. Example: aList = [ :one = 1 , :two = 2 , :three = 3 ] see aList["one"] + nl + aList["two"] + nl + aList["three"] + nl # print 1 2 3 see aList[1] # print one 1 Tip: using : before identifier (one word) means literal Note: using = inside list definition create a list of two items where the first item is the left side and the second item is the right side. We can add new items to the list using the string index Example: aList = [] aList["Egypt"] = "Cairo" aList["KSA"] = "Riyadh" see aList["Egypt"] + nl + # print Cairo aList["KSA"] + nl # print Riyadh 22.17 Passing Parameters Using List This type of lists is very good for passing parameters to functions Where the order of parameters will not be important (we can change the order). Also some parameters maybe optional. Example: 22.16. Access List Items by String Index 110
- 4. Ring Documentation, Release 1.3 myconnect ( [ :server = "myserver.com" , :port = 80 , :username = "mahmoud" , :password = "password" ] ) func myconnect mypara # print connection details see "User Name : " + mypara[:username] + nl + "Password : " + mypara[:password] + nl + "Server : " + mypara[:server] + nl + "Port : " + mypara[:port] 22.18 Swap Items We can swap the list items using the Swap() function. Example: aList = [:one,:two,:four,:three] see aList see copy("*",50) + nl swap(aList,3,4) see aList Output one two four three ************************************************** one two three four 22.18. Swap Items 111
- 5. CHAPTER TWENTYTHREE STRINGS In this chapter we are going to learn about strings creation and manipulation. 23.1 String Literals Syntax: cStr = "This is a string" cStr2 = 'Another string' cStr3 = :JustAnotherString cStr4 = `Yet "another" 'string' ! ` 23.2 Get String Length We can get the string length (letters count inside a string) using the len() function Syntax: len(string) ---> string length Example: cStr = "How are you?" see cStr + nl see "String size : " + len(cStr) + nl 23.3 Convert Letters Case Syntax: lower(string) ---> convert string letters to lower case upper(string) ---> convert string letters to UPPER case Example: cStr = "Welcome To The Ring Programming Language" see cStr + nl + upper(cStr) + nl + lower(cStr) 112
- 6. Ring Documentation, Release 1.3 23.4 Access String Letters We can access a letter inside a string by the letter index Syntax: string[index] ---> get string letter string[index] = letter # set string letter Example: # print user name letter by letter (each letter in new line) See "Hello, Enter your name : " give cName for x = 1 to len(cName) see nl + cName[x] next We can use for in to get string letters. Example: # print user name letter by letter (each letter in new line) See "Hello, Enter your name : " give cName for x in cName see nl + x next We can modify the string letters Example: # convert the first letter to UPPER case See "Enter your name : " give cName cName[1] = upper(cName[1]) see "Hello " + cName 23.5 Left() Function We can get a specified number of characters from a string using the Left() function. The starting position is 1. Syntax: Left(string,count) Example: see left("Hello World!",5) # print Hello 23.6 Right() Function We can get a specified number of characters from a string using the Right() function. 23.4. Access String Letters 113
- 7. Ring Documentation, Release 1.3 The starting position is the last character on the right. Syntax: Right(string,count) Example: see Right("Hello World!",6) # print World! 23.7 Trim() Function We can remove all leading and trailing spaces from a string using the Trim() function. Syntax: trim(string) Example: cMsg = " Welcome " see trim(cMsg) # print Welcome 23.8 Copy() Function We can duplicate a string more than one time using the copy() function. Syntax: copy(string,nCount) ---> string replicated nCount times Example see copy("***hello***",3) # print ***hello******hello******hello*** 23.9 Lines() Function We can count the number of lines inside a string using the Lines() function. Syntax: lines(string) ---> Number of lines inside the string Example: cStr = "Hello How are you? are you fine?" see lines(cStr) # print 3 23.7. Trim() Function 114
- 8. Ring Documentation, Release 1.3 23.10 Substr() Function We can work on sub strings inside a string using the substr() function. Using Substr() we can • Find substring • Get substring from position to end • Get Number of characters from position • Transform Substring To Another Substring 23.11 Find substring Syntax: substr(string,substring) ---> the starting position of substring in string Example: cStr = "Welcome to the Ring programming language" see substr(cStr,"Ring") # print 16 23.12 Get substring from position to end Syntax: substr(string,position) ---> Get substring starting from position to end Example: cStr = "Welcome to the Ring programming language" nPos = substr(cStr,"Ring") # nPos = 16 see substr(cStr,nPos) # print Ring programming language 23.13 Get Number of Characters From Position Syntax: substr(string,position,count) ---> Get characters starting from position Example: cStr = "Welcome to the Ring programming language" nPos = substr(cStr,"Ring") # nPos = 16 see substr(cStr,nPos,4) # print Ring 23.14 Transform Substring To Another Substring Syntax: 23.10. Substr() Function 115
- 9. Ring Documentation, Release 1.3 substr(string,substring,newsubstring) ---> Transformed string (Match case) substr(string,substring,newsubstring,1) ---> Transformed string (Ignore case) Example: cStr = "Welcome to the New programming language" see substr(cStr,"New","Ring") + nl # print Welcome to the Ring programming language see substr(cStr,"new","Ring",1)+ nl # print Welcome to the Ring programming language 23.15 strcmp() Function We can compare between two strings using the strcmp() function. Syntax: strcmp(cString1,cString2) ---> value = 0 if cString1 = cString2 value < 0 if cString1 < cString2 value > 0 if cString1 > cString2 Example: see strcmp("hello","hello") + nl + strcmp("abc","bcd") + nl + strcmp("bcd","abc") + nl Output: 0 -1 1 23.16 str2list() and list2str() Functions We can convert string lines to list items using the str2list() function. Also we can convert the list to a string using list2str() function. Syntax: str2list(string) ---> list contains the string lines list2str(list) ---> string contains the list items Example: /* output: ** Items : 4 ** Item : Hello ** Item : How are you ? ** Item : are you fine ? ** Item : ok ** list2Str result = Hello ** How are you ? ** are you fine ? ** ok ** Done */ 23.15. strcmp() Function 116
- 10. Ring Documentation, Release 1.3 mystr = "Hello How are you ? are you fine ? ok" mylist = str2list(mystr) see "Items : " + len(mylist) + nl for x in mylist see "Item : " + x + nl next newstr = list2str(mylist) see "list2Str result = " + newstr if mystr = newstr see nl + "Done" else see nl + "Error!" ok 23.16. str2list() and list2str() Functions 117