String append

From Rosetta Code
Task
String append
You are encouraged to solve this task according to the task description, using any language you may know.

Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.

You may see other such operations in the Basic Data Operations category, or:

Integer Operations
Arithmetic | Comparison

Boolean Operations
Bitwise | Logical

String Operations
Concatenation | Interpolation | Comparison | Matching

Memory Operations
Pointers & references | Addresses

Most languages provide a way to concatenate two string values, but some languages also provide a convenient way to append in-place to an existing string variable without referring to the variable twice.


Task

Create a string variable equal to any text value.

Append the string variable with another string literal in the most idiomatic way, without double reference if your language supports it.

Show the contents of the variable after the append operation.

ALGOL 68

Works with: ALGOL 68 version Revision 1.
Works with: ALGOL 68G version Any - tested with release algol68g-2.7.
Works with: ELLA ALGOL 68 version Any (with appropriate job cards).
File: String_append.a68
#!/usr/bin/a68g --script #
# -*- coding: utf-8 -*- #
 
STRING str := "12345678";
str +:= "9!";
print(str)
Output:
123456789!

AutoHotkey

s := "Hello, "
s .= "world."
MsgBox % s
Output:
Hello, world.

AWK

 
# syntax: GAWK -f STRING_APPEND.AWK
BEGIN {
s = "foo"
s = s "bar"
print(s)
exit(0)
}
 
Output:
foobar

Axe

Lbl STRCAT
Copy(r₂,r₁+length(r₁),length(r₂)+1)
r₁
Return

BASIC

Applesoft BASIC

S$ = "Hello"
S$ = S$ + " World!"
PRINT S$

BBC BASIC

      S$="Hello"
S$+=" World!"
PRINT S$
END
Output:
Hello World!

Bracmat

str="Hello";
str$(!str " World!"):?str;
out$!str;
Output:
Hello World!

C

#include<stdio.h>
#include<string.h>
 
int main()
{
char str[24]="Good Morning";
char *cstr=" to all";
char *cstr2=" !!!";
int x=0;
//failure when space allocated to str is insufficient.
 
if(sizeof(str)>strlen(str)+strlen(cstr)+strlen(cstr2))
{
/* 1st method*/
strcat(str,cstr);
 
/*2nd method*/
x=strlen(str);
sprintf(&str[x],"%s",cstr2);
 
printf("%s\n",str);
 
}
return 0;
}
Output:
Good Morning to all !!!

C++

#include <iostream>
#include <string>
 
int main( ) {
std::string greeting( "Hello" ) ;
greeting.append( " , world!" ) ;
std::cout << greeting << std::endl ;
return 0 ;
}
Output:
Hello , world!

C#

class Program
{
static void Main(string[] args)
{
string x = "foo";
x += "bar";
System.Console.WriteLine(x);
}
}

Clojure

Using global vars.

user=> (def s "app")
#'user/s
user=> s
"app"
user=> (def s (str s "end"))
#'user/s
user=> s
"append"

Using local bindings.

 
user=> (let [s "ap", s (str s "pend")] s)
"append"

COBOL

COBOL is not really a variable length field programming language. Most data items are fixed in size at compile time.

This example uses OCCURS DEPENDING ON, and reference modification to simulate a string append, all within an already maximally bounded character field. This type of programming task, while possible, is not overly common in COBOL applications.

Works with: GnuCOBOL
      identification division.                                         
program-id. string-append.
 
data division.
working-storage section.
01 some-string.
05 elements pic x occurs 0 to 80 times depending on limiter.
01 limiter usage index value 7.
01 current usage index.
 
procedure division.
append-main.
 
move "Hello, " to some-string
 
*> extend the limit and move using reference modification
set current to length of some-string
set limiter up by 5
move "world" to some-string(current + 1:)
display some-string
 
goback.
end program string-append.
 
Output:
$ cobc -xj string-append.cob
Hello, world

CoffeeScript

Works with: Node.js
a = "Hello, "
b = "World!"
c = a + b
 
console.log c

Or with concat:

console.log "Hello, ".concat "World!"
Output:
Hello, World!

Common Lisp

Similar to the Racket solution, a macro is necessary to append in-place:

(defmacro concatenatef (s &rest strs) 
"Append additional strings to the first string in-place."
`(setf ,s (concatenate 'string ,s ,@strs)))
(defvar *str* "foo")
(concatenatef *str* "bar")
(format T "~a~%" *str*)
(concatenatef *str* "baz" "abc" "def")
(format T "~a~%" *str*)

Output:

foobar
foobarbazabcdef

D

import std.stdio;
 
void main() {
string s = "Hello";
s ~= " world!";
writeln(s);
}
Output:
Hello world!

EchoLisp

 
;; Solution from Common Lisp and Racket
(define-syntax-rule (set-append! str tail)
(set! str (string-append str tail)))
 
(define name "Albert")name
 
(set-append! name " de Jeumont-Schneidre")
name
"Albert de Jeumont-Schneidre"
 

Elena

program =
[
var s := String new:"Hello".
s += " World".
 
console writeLine:s readChar.
].

Elixir

iex(60)> s = "Hello"
"Hello"
iex(61)> s <> " World!"
"Hello World!"

Emacs Lisp

version 1

 
(defun glue (str1 str2)
(concat str1 str2) )
 

version 2

 
(defun glue (str1 str2)
(format "%s%s" str1 str2) )
 

Eval:

 
(setq str "Hello, ")
(setq str (glue str "World!") )
(insert str)
 

Output:

Hello, World!


Erlang

Output:
1> S = "Hello".
"Hello"
2> S ++ " world".
"Hello world"


Euphoria

 
sequence string = "String"
 
printf(1,"%s\n",{string})
 
string &= " is now longer\n"
 
printf(1,"%s",{string})
 
Output:
String
String is now longer

F#

Strings are immutable in .NET. To append (to the same variable) the variable has to be declared mutable.

let mutable x = "foo"
x <- x + "bar"
printfn "%s" x


Forth

Strings in Forth are simply named memory locations
 
create astring 256 allot \ create a "string"
 
s" Hello " astring PLACE \ initialize the string
 
s" World!" astring +PLACE \ append with "+place"
 
 

Test at the console

  ok
s" Hello " astring place ok
s" World!" astring +place ok
astring count type Hello World! ok
 

Fortran

Using deferred length character strings:

 
program main
 
character(len=:),allocatable :: str
 
str = 'hello'
str = str//' world'
 
write(*,*) str
 
end program main
 

FreeBASIC

' FB 1.05.0 Win64
 
Var s = "String"
s += " append"
Print s
Sleep
Output:
String append

Gambas

Public Sub Form_Open()
Dim sString As String = "Hello "
 
sString &= "World!"
Print sString
 
End

Output:

Hello World!

Go

s := "foo"
s += "bar"

Gosu

// Example 1
var s = "a"
s += "b"
s += "c"
print(s)
 
// Example 2
print("a" + "b" + "c")
 
// Example 3
var a = "a"
var b = "b"
var c = "c"
print("${a}${b}${c}")
Output:
abc
abc
abc

Icon and Unicon

In both languages you can:

 
procedure main()
s := "foo"
s ||:= "bar"
write(s)
end
 

Outputs:

->ss
foobar
->

Groovy

 
class Append{
static void main(String[] args){
def c="Hello ";
def d="world";
def e=c+d;
println(e);
}
}
 
Output:
Hello world

Haskell

 
main = putStrLn ("Hello" ++ "World")
 

J

   s=: 'new'
s
new
s=: s,' value' NB. append is in-place
s
new value

Java

String sa = "Hello";
sa += ", World!";
System.out.println(sa);
 
StringBuilder ba = new StringBuilder();
ba.append("Hello");
ba.append(", World!");
System.out.println(ba.toString());
Output:
Hello, World!
Hello, World!

JavaScript

Works with: Rhino
Works with: SpiderMonkey
var s1 = "Hello";
s1 += ", World!";
print(s1);
 
var s2 = "Goodbye";
// concat() returns the strings together, but doesn't edit existing string
// concat can also have multiple parameters
print(s2.concat(", World!"));
Output:
"Hello, World!"
"Goodbye, World!"

jq

jq's + operator can be used to append two strings, and under certain circumstances the += operator can be used as an abbreviation for appending a string to an existing string. For example, all three of the following produce the same output:
"Hello" | . += ", world!"
 
["Hello"] | .[0] += ", world!" | .[0]
 
{ "greeting": "Hello"} | .greeting += ", world!" | .greeting
However the += operator cannot be used with jq variables in the conventional manner. One could nevertheless use the technique illustrated by the following:
"Hello" as $a | $a | . += ", world!" as $a | $a

Julia

s = "Hello"
s *= ", world!"
Output:
"Hello, world!"

Kotlin

fun main(args: Array<String>) {
var s = "a"
s += "b"
s += "c"
println(s)
println("a" + "b" + "c")
val a = "a"
val b = "b"
val c = "c"
println("$a$b$c")
}
Output:
abc
abc
abc

Lasso

local(x = 'Hello')
#x->append(', World!')
#x
Output:
Hello, World!

Lingo

str = "Hello" 
put " world!" after str
put str
-- "Hello world!"

LiveCode

Livecode has an "after" keyword for this

local str="live"
put "code" after str

Output is "livecode"

Lua

Not possible as strings are immutable. We can demonstrate their immutability using 'self':

function string:show ()
print(self)
end
 
function string:append (s)
self = self .. s
end
 
x = "Hi "
x:show()
x:append("there!")
x:show()
Output:
Hi 
Hi 

You can of course concatentate them and store the result in the original variable name but that requires a double reference:

x = "Hi "
x = x .. "there!"
print(x)
Output:
Hi there!

Maple

a := "Hello";
b := cat(a, " World");
c := `||`(a, " World");
Output:
                            "Hello"
                         "Hello World"
                         "Hello World"

Mathematica

 
(* mutable strings are not supported *)
s1 = "testing";
s1 = s1 <> " 123";
s1
Output:
"testing 123"

NetRexx

s_ = 'Hello'
s_ = s_', world!'
say s_
Output:
Hello, world!

NewLISP

(setq str "foo")
 
(push "bar" str -1)
; or as an alternative introduced in v.10.1
(extend str "bar")
 
(println str)
 

Nim

var str = "123456"
str.add("78") # two ways
str &= "9!" # to append

Objeck

 
class Append {
function : Main(args : String[]) ~ Nil {
x := "foo";
x->Append("bar");
x->PrintLine();
}
}
 

OCaml

let () =
let s = Buffer.create 17 in
Buffer.add_string s "Bonjour";
Buffer.add_string s " tout le monde!";
print_endline (Buffer.contents s)
Output:
Bonjour tout le monde!


Oforth

StringBuffer new "Hello, " << "World!" << println

PARI/GP

Not supported in GP.

s = "Hello";
s = Str(s, ", world!")
Output:
%1 = "Hello, world!"

Pascal

Works with: Free Pascal version 2.6.2
program StringAppend;
{$mode objfpc}{$H+}
 
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes
{ you can add units after this };
 
var
s: String = 'Hello';
begin
s += ' World !';
WriteLn(S);
ReadLn;
end.

Output:

Hello  World !

Perl

my $str = 'Foo';
$str .= 'bar';
print $str;
Output:
Foobar

Perl 6

my $str = "foo";
$str ~= "bar";
say $str;
Output:
foobar

Phix

string s = "this string"        ?s
s &= " is now longer"  ?s
Output:
"this string"
"this string is now longer"

PicoLisp

(setq Str1 "12345678")
(setq Str1 (pack Str1 "9!"))
(println Str1)
Output:
"123456789!"

PL/I

Cat: procedure options (main);
declare s character (100) varying;
s = 'dust ';
s ||= 'bowl';
put (s);
end Cat;
dust bowl


Plain TeX

Works with any TeX engine

\def\addtomacro#1#2{\expandafter\def\expandafter#1\expandafter{#1#2}}
\def\foo{Hello}
Initial: \foo
 
\addtomacro\foo{ world!}
Appended: \foo
\bye

pdf or dvi output:

Initial: Hello
Appended: Hello world!

PowerShell

 
$str = "Hello, "
$str += "World!"
$str
 
Hello, World!

PureBasic

S$ = "Hello"
S$ = S$ + " Wo" ;by referencing the string twice
S$ + "rld!" ;by referencing the string once
If OpenConsole()
PrintN(S$)
 
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf

Sample output:

Hello World!

Python

File: String_append.py
#!/usr/bin/env python
# -*- coding: utf-8 -*- #
 
str = "12345678";
str += "9!";
print(str)
Output:
123456789!

Racket

;there is no built-in way to set! append in racket
(define mystr "foo")
(set! mystr (string-append mystr " bar"))
(displayln mystr)
 
;but you can create a quick macro to solve that problem
(define-syntax-rule (set-append! str value)
(set! str (string-append str value)))
 
(define mymacrostr "foo")
(set-append! mymacrostr " bar")
(displayln mystr)
Output:
foo bar
foo bar

REXX

using abutment

s='he'
s=s'llo world!'
Say s

output

hello world!

using concatenation

s="He"
s=s || 'llo, World!' /*same as: s=s||'llo, World!' */
say s

output

Hello, World!

Ring

 
aString1 = "Welcome to the "
aString2 = "Ring Programming Language"
aString3 = aString1 + aString2
see aString3
 

Ruby

s = "Hello wo"
s += "rld" # new string object
s << "!" # mutates in place, same object
puts s
Output:
Hello world!


Rust

 
use std::ops::Add;
 
fn main(){
let hello = String::from("Hello world");
println!("{}", hello.add("!!!!"));
}
Output:

Hello world!!!!

Scala

An evaluation in Scala worksheet.

  var d = "Hello" // Mutables are discouraged     //> d  : String = Hello
d += ", World!" // var contains a totally new re-instantiationed String
 
val s = "Hello" // Immutables are recommended //> s  : String = Hello
val s1 = s + s //> s1  : String = HelloHello
val f2 = () => " !" //Function assigned to variable
//> f2  : () => String = <function0>
println(s1 + f2()); //> HelloHello !

Seed7

$ include "seed7_05.s7i";
 
const proc: main is func
local
var string: str is "12345678";
begin
str &:= "9!";
writeln(str);
end func;
Output:
123456789!

Sidef

var str = 'Foo';
str += 'bar';
say str;
Output:
Foobar

SNOBOL4

     s = "Hello"
s = s ", World!"
OUTPUT = s
END
Output:
Hello, World!

Swift

var s = "foo"              // "foo"
s += "bar" // "foobar"
print(s) // "foobar"
s.appendContentsOf("baz") // "foobarbaz"
print(s) // "foobarbaz"

Tcl

String concatenation is a fundamental feature of the Tcl language, and there is also an append that makes concatenation even simpler:

set s "he"
set s "${s}llo wo"; # The braces distinguish varname from text to concatenate
append s "rld"
puts $s
Output:
hello world

Ursa

decl string str
set str "hello "
 
# append "world" to str
set str (+ str "world")
 
# outputs "hello world"
out str endl console

VBA

Function StringAppend()
Dim s As String
s = "foo"
s = s & "bar"
Debug.Print s
End Function

VBScript

s = "Rosetta"
s = s & " Code"
WScript.StdOut.Write s
Output:
Rosetta Code

Wart

s <- "12345678"
s <- (s + "9!")

zkl

zkl strings are immutable, but byte blobs are mutable.

var s="foo";
s.append("bar"); //-->new string "foobar", var s unchanged
s+="bar"; //-->new string "foobar", var s modifed to new value
 
s=Data(Void,"foo"); // byte blob/character blob/text editor buffer
s.append("bar"); // or s+="bar"
s.text; //-->"foobar"