4.2 KiB
String Functions
string-related functions.
@parent js/language
The following string related functions are available in Touch Develop for the BBC micro:bit:
- equals - find out if two strings are the same
- at - get a character within a string
- concat - combine two strings
- count - get the number of characters in a string
- substring - get a portion of a string
- to character code - converts a character into a character code
- to number - converts a string into a number
Select a string variable in the Touch Develop editor to see the following string functions:
/* placeholder */
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let str = "hi"
~
equals
find out if two strings are the same
Syntax
String -> equals (other : String) returns Boolean
Parameters
- other - String; a string
Example
the following code does something if str = "Hi":
if (str == "Hi") {
// add code to do something here
}
at
get a character within a string, using the specified index
Syntax
String -> at (index: Number) returns String
Parameters
- index- Number; the character number within a string (0 returns the first character)
Example
The following code gets the first character from the str string and stores it in the first char variable:
let firstChar = str[0]
The || operator
To combine two strings you can use the string concatenation operation || as shown below:
let s = "abc" + "def"
let evaluatesToTrue = s == "abcdef"
NOTE: position the cursor outside of the string quotes, right after the string, for the || operator to appear in the keyboard.
concat
combine two strings; like the concat operator (||)
Syntax
String -> concat (other : String) returns String
Parameters
- other- String; a string
Example
The following code combines two strings and displays the string on screen:
str = "Hi "
str = str.concat("there")
basic.showString(str, 100)
count
get the number of characters in a string
Syntax
String -> count returns Number
Example
The following example gets the length of the str variable and stores it in the x variable:
let x = str.length
Substring
get a portion of a string, using a starting point and length
Syntax
String -> substring (start : Number, length : Number) returns String
Parameters
- start - Number; the starting character number (0 is the first character number in a string)
- length - Number; the string length
Example
The following code gets characters 6, 7, and 8 from the str string:
let asubstring = str.substr(5, 3)
to character code
converts the first character of a string into a character code number (unicode)
Syntax
String -> to character code returns Number
Example
The following code converts the first character of str into a character code and stores the code in x:
x = str.toCharacterCode()
to number
converts a string into a number
Syntax
String -> to number returns Number
Example
The following code converts str into a number and stores it in x:
x = parseFloat(str)