Language Sheet

syntax

hello world

#include <stdio.h>
int main(int argc, char **argv) {
printf("Hello, World!\n");
return 0;
}

#include <iostream>
using namespace std;
int main(int argc, char **argv) {
cout << "Hello, World!" << endl;
return 0;
}

console.log 'Hello, World!'

public class Hello {
  public static void main(String[] args) {
    System.out.println("Hello, World!");
  }
}

console.log('Hello, World!');

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print('Hello, World!')

#import <Foundation/Foundation.h>
int main(int argc, char **argv) {
NSLog(@"Hello, World!");
return 0;
}

print_endline "Hello, World!";;

print "Hello, World!\n";

<?
echo "Hello, World!\n";
?>

print 'Hello, World!'

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(display "Hello, World!\n")

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extensions

.c - source
.h - header

.cpp, .cc, .C, .cxx - source
.h, .hpp, .hh, .H, .hxx - header

.coffee, .litcoffee

.java - source
.class - compiled object

.js

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.lua

.m - source
.mm - source with C++
.h - header

.ml

.pl

.php

.py

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.scm

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block delimiters

{}

indentation

{}

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{}

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{}

indentation

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parentheses

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statement terminator

semicolon

newline

semicolon

semicolon, but sometimes optional

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newline or semicolon

semicolon

double semicolon

semicolon

newline

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parentheses matching

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import file/module

#include <filename>

#include "filename"

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to this language

import packagename.classname;

import packagename.*;

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to this language

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end-of-line comment

// comment

# comment

// comment

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# comment

// comment

# comment

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block comment

/* comment */

###
comment
###

/* comment */

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=pod
comment
=cut

/* comment */

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variable

assignment

a = 7;

a = 7

a = 7;

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a = 7;

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$a = 7;

a = 7

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swap

// basic
tmp = x;
x = y;
y = tmp;

// function
void swap(int *a, int *b) {
  int tmp;
  tmp = *b;
  *b = *a;
  *a = tmp;
}
swap(&x, &y);

// no temporary variable
x = x + y;
y = x - y;
x = x - y;

// no temporary variable 2
x = x ^ y;
y = x ^ y;
x = x ^ y;

swap(x, y);

[x, y] = [y, x]

tmp = x;
x = y;
y = tmp;

// basic
tmp = x;
x = y;
y = tmp;

// tricky one-line
x = [y, y = x][0];

// ES2015 (ES6)
[x, y] = [y, x]

tmp = x
x = y
y = tmp

x, y = y, x

tmp = x;
x = y;
y = tmp;

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($x, $y) = ($y, $x);

// basic
list($x, $y) = array($y, $x);

// function
function swap(&$x, &$y) {
  $tmp = $x;
  $x = $y;
  $y = $tmp;
}

x, y = y, x

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swap(&x, &y)

arithmetic

power

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Math.pow(2.5, 13.2);

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square root

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Math.sqrt(1.69);

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logic

boolean type

int

bool

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boolean

Not applicable
to this language

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Not applicable
to this language

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string

concatenate

const char *s1 = "hello";
const char *s2 = " world";
char *s3 = (char *)malloc(strlen(s1)+strlen(s2)+1);
strcpy(s3, s1);
strcat(s3, s2);

// destructive
string s1 = "hello";
s1 += " world";

// non-destructive
string s1 = "hello";
string s2 = s1 + " world";

'hello' + ' world'

"hello" + " world"

'hello' + ' world'

"hello" + " world"

'hello' .. ' world'

// destructive
NSMutableString *s1 = [@"hello" mutableCopy];
[s1 appendString:@" world"];

// non-destructive
NSString *s1 = @"hello";
NSString *s2 = [s1 stringByAppendingString:@" world"];

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'hello' . ' world'

'hello' + ' world'

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"hello" + " world"

convert case

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"hello".toUpperCase();
"HELLO".toLowerCase();

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[@"hello" uppercaseString];
[@"HELLO" lowercaseString];

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trim

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" hello ".trim();

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[@" hello " stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

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format string

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[NSString stringWithFormat:@"str-%@, int-%d, num-%f", @"Lang", 5, 9.4];

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join a string array

const char *const strs[] = {"one", "two", "three"};
int i = 0;
int size = 0;
char *out;
for (i=0;i<3;i++) {
  size += strlen(strs[i]) + 1;
}
out = (char *)malloc(size);
strcpy(out, strs[0]);
for (i=1;i<3;i++) {
  strcat(out, ",");
  strcat(out, strs[i]);
}

// one-liner
vector<string> strs = {"one", "two", "three"};
string out = accumulate(next(strs.begin()), strs.end(), strs[0],
  [](const string &a, const string &b) {
    return a + "," + b;
  });

// prevent reallocation
vector<string> strs = {"one", "two", "three"};
ostringstream os;
copy(strs.begin(), strs.end()-1, ostream_iterator<string>(os, ","));
os << *strs.rbegin();
string out = os.str();

strs = ['one','two','three']
out = strs.join ','

// Java 8
List<String> strs = Arrays.asList("one", "two", "three");
String out = String.join(",", strs);

// Java 7 and below
String[] strs = {"one", "two", "three"};
StringBuilder sb = new StringBuilder();
boolean first = true;
for (String str : strs) {
  if (first) {
    first = false;
  } else {
    sb.append(",");
  }
  sb.append(str);
}
String out = sb.toString();

let strs = ['one','two','three']
let out = strs.join(',')

val strs = arrayOf("one", "two", "three")
val out = strs.joinToString(",")

strs = {"one", "two", "three"}
table.concat(strs, ",")

NSArray *strs = @[@"one", @"two", @"three"];
NSString *out = [strs componentsJoinedByString:@","];

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@strs = qw(one two three);
$out = join ',', @strs;

$strs = array('one', 'two', 'three');
$out = implode(',', $strs);

strs = ['one','two','three']
','.join(strs)

strs = %w(one two three)
out = strs.join ','

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let strs = ["one", "two", "three"]
let out = strs.joined(separator: ",")

split a string

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[@"a,b,c" componentsSeparatedByString:@","];

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function

define function

int sum(int x, int y, int z) {
return x + y + z;
}

sum = (x, y, z) ->
x + y + z

int sum(int x, int y, int z) {
return x + y + z;
}

function sum(x, y, z) {
return x + y + z;
}

var sum = function (x, y, z) {
return x + y + z;
};

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def sum(x, y, z):
return x + y + z

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invoke function

sum(1, 2, 3);

sum 1, 2, 3

sum(1, 2, 3)

sum(1, 2, 3);

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sum(1, 2, 3)

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default argument

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to this language

double logarithm(double x, double base=10) {
return log(x) / log(base);
}

logarithm = (x, base=10) ->
Math.log(x) / Math.log(base)

double logarithm(double x) {
return logarithm(x, 10);
}
double logarithm(double x, double base) {
return Math.log(x) / Math.log(base);
}

function logarithm(x, base) {
  if (base==null) {
    base = 10;
  }
  return Math.log(x) / Math.log(base);
}

fun logarithm(x: Double, base: Double=10.0): Double {
return Math.log(x) / Math.log(base)
}

function logarithm(x, base)
base = base or 10
return math.log(x) / math.log(base)
end}

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to this language

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sub logarithm {
  my $x = shift;
  my $base = shift // 10;
  log($x) / log($base);
}

function logarithm($x, $base=10) {
return log($x) / log($base);
}

def logarithm(x, base=10):
return math.log(x) / math.log(base)

def logarithm(x, base=10)
Math.log(x) / Math.log(base)
end

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func logarithm(x: Double, base: Double=10) -> Double {
return log(x) / log(base)
}

control flow statement

if (a<b) {
  order = -1;
} else if (a==b) {
  order = 0;
} else {
  order = 1;
}

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if (a<b) {
  order = -1;
} else if (a==b) {
  order = 0;
} else {
  order = 1;
}

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if ($a<$b) {
  $order = -1;
} elsif ($a==$b) {
  $order = 0;
} else {
  $order = 1;
}

if ($a<$b) {
  $order = -1;
} elseif ($a==$b) {
  $order = 0;
} else {
  $order = 1;
}

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resizable array

create

Not applicable
to this language

#include <vector>
std::vector<int> a;

a = new Array()

a = []

import java.util.ArrayList;
ArrayList a = new ArrayList();

// legacy class(slow due to synchronization)
import java.util.Vector;
Vector a = new Vector();

a = new Array();

a = [];

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@a = ();

$a = array();

$a = [];

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create with values

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a = new Array(1, 2, 3)

a = [1, 2, 3]

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to this language

a = new Array(1, 2, 3);

a = [1, 2, 3];

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regular expression

replace first

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String consonants = "hello".replaceFirst("[aeiou]", "");

import java.util.regex.Pattern;
String consonants = Pattern.compile("[aeiou]").matcher("hello").replaceFirst("");

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replace all

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String consonants = "hello".replaceAll("[aeiou]", "");

import java.util.regex.Pattern;
String consonants = Pattern.compile("[aeiou]").matcher("hello").replaceAll("");

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capturing group

const char *str = "2016-12-05";
regex_t rx;
if (regcomp(&rx, "([[:digit:]]{4})-([[:digit:]]{2})-([[:digit:]]{2})", REG_EXTENDED)==0) {
  regmatch_t m[4];
  if (regexec(&rx, str, 4, m, 0)==0) {
    int year = str2int(str+m[1].rm_so, m[1].rm_eo - m[1].rm_so);
    int month = str2int(str+m[2].rm_so, m[2].rm_eo - m[2].rm_so);
    int day = str2int(str+m[3].rm_so, m[3].rm_eo - m[3].rm_so);
  }
  regfree(&rx);
}

string str("2016-12-05");
regex rx("(\\d{4})-(\\d{2})-(\\d{2})");
smatch m;
if (regex_match(str, m, rx)) {
  int year = stoi(m.str(1));
  int month = stoi(m.str(2));
  int day = stoi(m.str(3));
}

str = '2016-12-05'
if /(\d{4})-(\d{2})-(\d{2})/.test str
  year = Number RegExp.$1
  month = Number RegExp.$2
  day = Number RegExp.$3

String str = "2016-12-05";
Pattern rx = Pattern.compile("(\\d{4})-(\\d{2})-(\\d{2})");
Matcher m = rx.matcher(str);
if (m.matches()) {
  int year = Integer.parseInt(m.group(1));
  int month = Integer.parseInt(m.group(2));
  int day = Integer.parseInt(m.group(3));
}

var str = '2016-12-05';
if (/(\d{4})-(\d{2})-(\d{2})/.test(str)) {
  var year = Number(RegExp.$1);
  var month = Number(RegExp.$2);
  var day = Number(RegExp.$3);
}

val str = "2016-12-05"
val rx = "(\\d{4})-(\\d{2})-(\\d{2})".toRegex()
val m = rx.matchEntire(str)
if (m!=null) {
  val year = m.groups[1]!!.value.toInt()
  val month = m.groups[2]!!.value.toInt()
  val day = m.groups[3]!!.value.toInt()
}

str = '2016-12-05'
rx = '(%d%d%d%d)-(%d%d)-(%d%d)'
year, month, day = string.match(str, rx)
year = tonumber(year)
month = tonumber(month)
day = tonumber(day)

NSString *str = @"2016-12-05";
NSRegularExpression *rx = [NSRegularExpression regularExpressionWithPattern:@"(\\d{4})-(\\d{2})-(\\d{2})" options:0 error:nil];
NSTextCheckingResult *m = [rx firstMatchInString:str options:0 range:NSMakeRange(0, [str length])];
if (m!=nil) {
  NSInteger year = [[str substringWithRange:[m rangeAtIndex:1]] integerValue];
  NSInteger month = [[str substringWithRange:[m rangeAtIndex:2]] integerValue];
  NSInteger day = [[str substringWithRange:[m rangeAtIndex:3]] integerValue];
}

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$str = '2016-12-05';
$rx = qr/(\d{4})-(\d{2})-(\d{2})/;
if ($str =~ $rx) {
($year, $month, $day) = (int $1, int $2, int $3);
}

$str = '2016-12-05';
$rx = '/(\d{4})-(\d{2})-(\d{2})/';
if (preg_match($rx, $str, $m)) {
  $year = (int)$m[1];
  $month = (int)$m[2];
  $day = (int)$m[3];
  // if you don't need integers
  list($_, $year, $month, $day) = $m;
}

str = '2016-12-05'
rx = '(\\d{4})-(\\d{2})-(\\d{2})'
m = re.search(rx, str)
if m:
  year = int(m.group(1))
  month = int(m.group(2))
  day = int(m.group(3))
  // if you don't need integers
  year, month, day = m.groups()

// using method
str = '2016-12-05'
rx = /(\d{4})-(\d{2})-(\d{2})/
m = rx.match(str)
if m
  year = m[1].to_i
  month = m[2].to_i
  day = m[3].to_i
  // if you don't need integers
  year, month, day = m[1..3]
end

// using pattern-matching operator
str = '2016-12-05'
rx = /(\d{4})-(\d{2})-(\d{2})/
if rx =~ str
  year = $~[1].to_i
  month = $~[2].to_i
  day = $~[3].to_i
  // if you don't need integers
  year, month, day = $~[1..3]
end

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let str = "2016-12-05"
let rx = try! NSRegularExpression(pattern: "(\\d{4})-(\\d{2})-(\\d{2})", options: [])
if let m = rx.firstMatch(in: str, options: [], range: NSRange(location: 0, length: (str as NSString).length)) {
  let year = Int((str as NSString).substring(with: m.rangeAt(1)))
  let month = Int((str as NSString).substring(with: m.rangeAt(2)))
  let day = Int((str as NSString).substring(with: m.rangeAt(3)))
}

date

current Unix time

time_t now = time(NULL);

time_t now = time(nullptr);

now = Date.now() / 1000

now = new Date().getTime() / 1000

long now = System.currentTimeMillis() / 1000;

long now = new Date().getTime() / 1000;

now = Date.now() / 1000;

now = new Date().getTime() / 1000;

val now = System.currentTimeMillis() / 1000

val now = Date().getTime()/1000

now = os.time()

NSTimeInterval now = [[NSDate date] timeIntervalSince1970];

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$now = time;

$now = time();

time.time()

now = Time.now.to_i

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let now = Date().timeIntervalSince1970

object-oriented programming

define class

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public class Shape2D {
  private double x;
  private double y;
  public Shape2D(double x, double y) {
    this.x = x;
    this.y = y;
  }
  public void move(double dx, double dy) {
    x += dx;
    y += dy;
  }
}

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create object

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Shape2D s = new Shape2D(5, 3);

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invoke method

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s.move(2, 4);

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subclass

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public class Circle extends Shape2D {
  private double radius;
  public Circle(double x, double y, double radius) {
    super(x, y);
    this.radius = radius;
  }
}

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root class

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java.lang.Object

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