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Strings

To define a string use String type, to access a character of the string, use index [] operator or the member function get(<index>).

<string>:String = "This is a string"
<string>[3] // is equal to s
<string>.get(3) // is equal to s

String are immutable, modifying a string means to create a new one.

Escape sequences

Escape	Charater
\t	tab
\b	bell
\r	carriage return
\n	line feed
\'	'
\"	"
\	\
\$	$

Concatenate

Use operator +
Use string template (see below)
Use string builder (see below)

String template

When a string variable is put into another string preceded by $ the content of the string is substituted. It is also possible to enclose expressions in curly brackets preceded by $, in this case the expression is evaluated and "converted" to string.

a:String = "This is a string"
b:String = "$a too"  // result is: "This is a string too"
c:String = "Result is ${3 * 3}" // result is: "Result is 9"

String builder

Example:

val str1 = "first string"
val str2 = " second string"

val sb = StringBuilder()
sb.append(str1).append(str2)
val str4 = sb.toString()  //result is: "first string second string"

println("$str4\n")

Raw strings

Are multi-line string defined using triple ".
Support String template
Do not support escape sequences
Are somehow "literal": this means that indentation spaces are put into the raw string. A possible solution for that problem (i.e. using indented multi-line raw string and avoid that indentations spaces come up into the string) is to use the TrimMargin String member function: this function removes all leading whitespace up to a certain character (by default this character is |), also that character is removed from the string.

For example with:

    val multi = """This is 
         an indented multi-line raw string
         plus some stuff to get long
         multi-line example"""

    println("$multi\n")

    val multi1 = """In this case we avoid
the indentation of the multi-line raw string
plus some stuff to get long
multi-line example"""

    println("$multi1\n")

    val multi2 = """Or you can indent and trim the 
                  |the indentation of the multi-line raw string
                  |plus some stuff to get long
                  |multi-line example""".trimMargin()

    println("$multi2\n")

you get

raw strings in kotlin

String length

<string>.lenght

Compare string

Method 1:

<string1>.equals(<string2>)

returns true or false

Method 2:

<string1> == <string2>

Method 3:

<string1>.compareTo(<string2>)

Returns:

0 if <string1> is equal to <string2>
a negative number if <string1> it's less than <string2>
a positive number if <string1> it's greater than <string2>

Get a substring

<string>.subSequence(<from index>, <to index>)

<from index> is included <to index> is excluded

Is sub-string contained?

<string1>.contains(<string2>)

return true if <string1> contains <string2>