evolve

Strings

The following statements can be used to manipulate strings.

Adding to a string

The str_add command can be used to add two strings or a string and another variable type together, this is demonstrated in the following code. It can be used to add multiple values into a string by simply appending the addition values to the end of the command.

str_add Str1 IntVar " test " 0x32

//---------------------------------------

// File: StringAdd.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//define some variables

Str1 = "add "

Str2 = "test "

IntVar = 10

//add different data types to string

str_add Str1 Str2

outl Str1

str_add Str1 "="

outl Str1

str_add Str1 " "

outl Str1

//Add multiple items

str_add Str1 IntVar " test " 0x32

outl Str1

_block

Finding a String within a String

The str_find command allows you to find the occurrence of one string within another the command takes four arguments. The first argument should be passed an integer variable to store the position of the found string in, if the string is not found then the command will return the position 0xFFFF. The second argument is the string to search within, the third argument is the string to search for and the final argument is the position within the string to start the search at. The str_findr command is the same but searches backwards through the string.

So the following line will return the position of 'token' in Str1 starting at the first character, the variable TokenPosition will be set to the index of the start of 'token' in Str1

str_find TokenPosition Str1 "token" 0

The following example shows str_find and str_findr in action.

//---------------------------------------

// File: StringFind.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//define a string

Str1 = "token1, token2, token3, token4 "

//find the tokens

str_find TokenPosition Str1 "token" 0

while TokenPosition != 0xFFFF

outl "Token found at:" TokenPosition

++ TokenPosition

str_find TokenPosition Str1 "token" TokenPosition

_while

//find the tokens in the reverse direction

str_len TokenPosition Str1

while TokenPosition != 0xFFFF && TokenPosition != 0

-- TokenPosition

str_findr TokenPosition Str1 "token" TokenPosition

outl "Token found at:" TokenPosition

_while

_block

Searching in a string using a Regular Expression

Strings can be searched using regular expressions these allow data to be extracted using a template. The str_regex command the syntax is

str_regex <container list> <string> <regular expression>

The first variable is a container list where any results of found strings and the positions are returned. If no matches are found then the list will be empty. The second variable is the string that will be searched and the third variable is the regular expression to be found. The container that is returns contains 2 variables .Str is the found matching string and .Pos is the position of the found string. The following example shows how it works. For more information on regular expressions look on line.

//---------------------------------------

// File: StringRegExe.e

//---------------------------------------

// Block: Go

//---------------------------------------

block Go

Test = "this subject has a submarine as a subsequence"

RegEx = "\b(sub)([^ ]*)"

str_regex @Result Test RegEx

lst_size Size Result_Pos

loop I Size

outl Result.Pos[I] " " Result.Str[I]

_loop

_block

Searching in a using wild card expression

Strings can be searched using wild card expressions these allow data to be extracted using a template. The str_wild command the syntax is

str_wild <result container> <string> <wild card expression> <start pos>

The first variable is a container list where any results of found strings and their positions are returned. If no matches are found then the list will be empty. The second variable is the string that will be searched, the third variable is the regular expression to be found. The final one is the position in the string to start the search from this argument is optional, if it is not included then the search will be recursive until the end of the string is found. The wild card symbol is *.

So if you wanted to search a string for all instances of words wrapped in parenthesis then the search string would be (*). The following example shows this after the command is run the Result list should have 3 entries '1', 'name' and 'word'.

str_wild Result “(1) some text (name) more text (word)” “(*)”

The following example shows how it works.

//---------------------------------------

// File: StrWild.e

//---------------------------------------

// Block: Go

//---------------------------------------

block Go

//Non recursive example

Str = "ThisResult1TestResult2Help----ThisResult3TestResult4Help"

TestStr = "This*Test*Help"

str_wild @Result Str TestStr 0

outl Result.Str[0] " at " Result.Pos[0]

outl Result.Str[1] " at " Result.Pos[1]

new_line

str_wild @Result Str TestStr 15

outl Result.Str[0] " at " Result.Pos[0]

outl Result.Str[1] " at " Result.Pos[1]

new_line

//Recursive example

Str = "ThisResult1TestResult2Help----ThisResult3TestResult4Help"

TestStr = "This*Test*Help"

str_wild @Result Str TestStr

outl Result.Str[0] " at " Result.Pos[0]

outl Result.Str[1] " at " Result.Pos[1]

outl Result.Str[2] " at " Result.Pos[2]

outl Result.Str[3] " at " Result.Pos[3]

_block

Replacing a Substring

A substring of a string can be replaced with another string using the str_replace command. The commands syntax is as follows.

str_replace <string> <find string> <replace string>

It searches the string with the string to find and replaces any occurrences with the replacement string.

//---------------------------------------

// File: StringReplace.e

//---------------------------------------

// Block: Go

//---------------------------------------

block Go

Str = "this is my test"

str_replace Str "my" "your"

outl Str

//mulitple finds

Str = "this is my test my test"

str_replace Str "my" "your"

outl Str

//replace with value

Str = "this is test10"

str_replace Str "10" 20

outl Str

//single character

Str = "aaaaaaaaaaaaaaa"

str_replace Str "a" "b"

outl Str

_block

Getting a Substring

The str_sub command allows extraction of part of a string, the command takes the following arguments the destination string, the source string, the character to start at and the number of characters to get. The following line of code will set SubStr to the two charcters that start at index three so it would equal 'de'.

str_sub SubStr “abcdefg” 3 2

This is demonstrated in the following code

//---------------------------------------

// File: StringSub.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

TOKENSIZE = 6

//define a string

Str1 = "token1, token2, token3, token4"

//find the tokens

str_find TokenPosition Str1 "token" 0

while TokenPosition != 0xFFFF

//get the token from the string

str_sub Token Str1 TokenPosition TOKENSIZE

//display the token

outl Token

++ TokenPosition

str_find TokenPosition Str1 "token" TokenPosition

_while

_block

Splitting a String

The str_split command can be used to split a string to the left or the right of an index within the string. The command take three arguments a string to return to the new sub string, the string to split, the index to split the string and a constant #LEFT or #RIGHT to define which section of the string should be returned. The returned string will contain the sub string to the left or right of the index excluding the character at the index.

//---------------------------------------

// File: StringSplit.e

//---------------------------------------

// Block: Go

//---------------------------------------

block Go

Str = "Split this String"

str_split Str1 Str 5 #LEFT

outl Str1

str_split Str1 Str 5 #RIGHT

outl Str1

_block

Other String Statements

str_len is used to get the length of a string the string is the second argument and the length is returned in the first argument.

str_len Length “abcdefgh”

In the above line of code Length would be set to 8.

str_strtobyte takes three arguments The first is the byte to return the character in the second is the string to get the character from and the third is the index of the character to get.

str_strtobyte ByteVal “teststring” 3

In the above line of code ByteVal would be set to 116.

str_bytetostr converts a byte value into a string the first argument is the string and the second is the byte to convert to the string. The following code will to convert the ASCII value 117 to the string “A”.

str_bytetostr Str 117

These statements are demonstrated in the following code.

//---------------------------------------

// File: StringOther.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

TOKENSIZE = 6

//define a string

Str1 = "abcdfghijkl"

//display the length

str_len Length Str1

outl "Length: " Length

//loop displaying the bytes of the string

I = 0

while I < Length

str_strtobyte ByteValue Str1 I

outl "Char" I " = " ByteValue

++ I

_while

//Create a new string from bytes

Str1 = ""

ByteValue = 0x00

ByteValue = 'm'

//add bytes until get to z

while ByteValue < 'z'

//convert byte to string

str_bytetostr StrByte ByteValue

//add to main string

str_add Str1 StrByte

//increment the byte

++ ByteValue

_while

//display the strings

outl Str1

_block