Table of contents -> Chapter 8 - Functions for string type variables

The next topic is the description for the use of the following TEIMSI predefined functions:

1)- asc

2)- ascat

3)- chr

4)- chrat

5)- hashver

6)- hextostr

7)- isinsideof

8)- ke_hashxlen

9)- lcase

10)- left

11)- len

12)- ltrim

13)- makestring

14)- replace

15)- right

16)- rtrim

17)- scrc16b

18)- setascat

19)- setchrat

20)- str_count

21)- str_repeatn

22)- str_overwrite

23)- str_reverse

24)- strpos

25)- strposrev

26)- strtohex

27)- substr

28)- substring

29)- trim

30)- ucase

31)- loadszstring

asc

The "asc" function, receives a character and returns its ASCII code, an integer between 0 and 255 (inclusive). It is the inverse function of the function chr.

	alert(asc("@"))		//	Shows the integer 64.

ascat

The "ascat" function, returns the ASCII code of a character of a string sent to it.

	alert(ascat("Hello", 4))	//	Shows the ASCII code of the char "o", = 111

chr

The "chr" function, receives an integer between 0 and 255 (inclusive) and returns a character whose ASCII code is the number that was sent to it. It is the inverse function of the asc function.

	alert(chr(65))		//	Shows the character "A".

chrat

The "chrat" function, returns a character located in the string sent to it.

	alert(chrat("Hello",4))	//	Shows the character "o"

hashver

The "hashver" function, calculates a "hash" number (or CRC checksum) from a string that is sent as a parameter.

	alert(hashver("fire"))		//	Shows 1761614542

hextostr

The "hextostr" function, receives a string previously created with the strtohex function (it performs the inverse task that function).

	var string1=strtohex("@$")	//	string1 has now the string "4024"

	alert(hextostr(string1))	//	Shows the string "@$".

isinsideof

The "isinsideof" function, determines whether the first characters of a string match with those of another string that is also sent to it.

The advantage of this function resides on the speed to determine if part of a string matches with other one, since other code doing this task will surely be much more slow. It's performance is notable when you need to call the function thousands of times per second.

	alert(isinsideof("017-Ocean - Dreams", "-Ocean", 3))

		//	Determines if the string "-Ocean" is within the string "017-Ocean - Dreams" starting 
		//		from the position 3 (true).

ke_hashxlen

The "ke_hashxlen" function, returns a "hash" string (unique and not convertible to the source string by of reciprocal function), from the source string. It's the length of the output string can be specified and its characters can be on the whole range of the ASCII code (from 0 to 255 included).

The advantage of this function resides on its capability to return a "binary" string of arbitrary length, it also provides a "strong" method of calculation of the output string (and it is considerably slow).

	// Displays a "hash" string (similar to the one that generates the "MD5Hash" function, for more information search for "RFC1321" on the Internet).


	alert(strtohex(ke_hashxlen("Programming with TEIMSI", 16)))

lcase

The "lcase" function, converts the characters of a string to lowercase.

	alert(lcase("PROGRAM"))		//	Shows "program"

left

The "left" function, returns a string with is part of the left side of the string that it receives.

	alert(left("UltraRay", 5))		//	Shows the string "Ultra".

len

The "len" function, returns an integer with the length of a TEIMSI variable with a data type of string.

	alert(len("number"))		//	Shows "6"

ltrim

The "ltrim" function, receives a string and returns the result of removing spaces and tabs on its left side.

	alert("This is a " + ltrim("	  	text"))		// Shows "This is a text"

makestring

The "makestring" function, creates a string with the desired length, containing all the characters equal to the character with ASCII 0 which is chr(0).

	alert(len(makestring(29)))		// Shows "29"

replace

The "replace" function, returns a string which is the result of replacing inside the string it receives; all matches of a string for another.

	alert(replace("ello", "e", "He"))

right

The "right" function, returns a string with is part of the right side of the string it receives.

	alert(right("UltraRay", 3))		//	Shows the string "Ray".

rtrim

The "rtrim" function, receives a string and returns the result of removing spaces and tabs on its right side.

	alert("This is a " + rtrim("small	  	") + " text")		// Shows "This is a small text"

scrc16b

The "scrc16b" function, creates a unique string (CRC) from another. The resulting string has four hexadecimal characters (numbers and letters A, B, C, D, E, F)

		function s16b_crc($encs){
			$rslt = 799477;
			for($i=0;$i<strlen($encs);$i++){
				$rslt = $rslt ^ (ord($encs[$i])*175 + (($i*3+171)^7977) ) ;
			}
			$rslt=$rslt-65536*floor($rslt/65536);
			$rslt1=floor($rslt/256);
			$rslt2=$rslt-256*$rslt1;

			$s1="00".dechex($rslt1);
			$s2="00".dechex($rslt2);

			return( substr($s1, len($s1)-2, 2) . substr($s2, len($s2)-2, 2)     );
		}

	

	alert(scrc16b("hello"))		//	Shows "5B9F"

setascat

The "setascat" function, returns a string that comes from writing a character in an input string, whose write position and character ASCII code is specified. Reading this value is done with the function ascat.

	var cad1="Oceani"

	setascat(cad1, 5, 111)

	alert(cad1)					//	Shows the string "Oceano".

	alert(setascat("Oceuno", 3, 97))		//	Shows the string "Oceano".

setchrat

The "setchrat" function, returns a string that comes from writing a character in an input string in a specified position writing. The reading of the character is done with the function chrat.

	var cad1="Oceani"

	setchrat(cad1, 5, "o")

	alert(cad1)					//	Shows the string "Oceano".

	alert(setchrat("Oceani", 5, "o"))		//	Shows the string "Oceano".

str_count

The "str_count" function, receives two TEIMSI variables with string type and determines the number of times the second string is found within the first (except interpositions).

		alert(str_count("1111222211112222", "11"))		//	Show the number 4.

str_repeatn

The "str_repeatn" function, creates a string repeating another input string whose number of repetitions is indicated by an integer as the first parameter.

	alert(str_repeatn("*", 12))		//	Shows the string "************"

str_overwrite

The "str_overwrite" function, overwrites a portion of a string type variable. It receives as the first parameter a public variable or local to a TEIMSI function, and a second string type variable whose characters (bytes) will be written in the first one. The third parameter is a long integer (signed) with the displacement in the first string from where writing began. It support strings with length up to 2147483647 (That is, 2**31 - 1) bytes.

	var string1="wave of propagation"

	str_overwrite(string1, "in interaction", 5)

	alert(string1)

//Example 2

	//    The purpose of the function is to accelerate the process of replacing a partion of a string in TEIMSI language, it would otherwise be a slow task. As in the following example whose goal is to change the word "-center-" for "-string-" inside a known string variable. 

	var string1="left-center-right"

	var search  = "-center-"
	var change = "-string-"

	var p=strpos(string1, search, 0)

	//	Option 1 (slow)

		string1=substr(string1, 0, p) + change + substr(string1, p+len(search), -1)

	//	Option 2 (fastest)

		str_overwrite(string1, change, p)

str_reverse

The "str_reverse" function, receives a string and returns the string with all it's characters moved symmetrically respect of the center, (that is first characters appear as the last ones, and last characters as the first ones).

	alert(str_reverse("tol a"))		//	Shows the string "a lot"

strpos

The "strpos" function, seeks for a string within another starting from the specified position.

	alert(strpos("hello world", "ello", 0))		// Shows "1"
	alert(strpos("hello world", "ello", 2))		// Shows "-1"

strposrev

The "strposrev" function, searches for a string within another starting from the specified position from it's ending position to the starting position.

	alert(strposrev("hola ola.", "ola", 1000000))	// Shows "5"
	alert(strposrev("hola ola.", "ola", 3))		// Shows "1"

strtohex

The "strtohex" function, converts a string into another whose ASCII codes are glued, using an hexadecimal notation and length of 2 bytes.

	alert(strtohex("@$"))	//	Shows the string "4024", note that the ASCII code of "@" is 64 (or 40 hexadecimal) and the one of "$" is 36 (or 24 hexadecimal).

substr

The "substr" function, subtracts part of a string. It is similar to the function substring but differs in the third parameter.

	alert(substr("universe", 3, 5))		//	Shows the string "verse"

substring

The "substring" function, subtracts part of a string. It is similar to the function substr but differs in the third parameter.

	alert(substring("universe2", 3, 8))		//	Shows the string "verse"

trim

The "trim" function, removes spaces and tabs on the sides of an input string and returns the resulting string.

	alert("The electron is " + trim("	  	a 		") + " lepton")		// Shows "The electron is a lepton"

ucase

The "ucase" function, returns a string which is the result of convert the characters of the input string to uppercase.

	alert(ucase("program"))		//	Shows "PROGRAM"

loadszstring

The "loadszstring" function, loads a string defined in the assembler data section, the string must end with the character chr(0).

	place_idata{
		description db "The space is not empty.",0

	}
	var integer=0;
	_direct{
		mov [integer+reg.vo], (description)
	}
	alert(_c34+loadszstring(integer)+_c34);		//	Shows the string: "The space is not empty."