Corpus-NZ/Code-Syntax-Expanded · Datasets at Hugging Face

wrong_code stringlengths 3 123	correct_code stringlengths 3 155	explanation stringclasses 101 values	language stringclasses 26 values
my @arr = (36,5,38);	my @arr = (36,5,38);	Correct.	Perl
$data[29] = 5;	if (isset($data[29])) $data[29] = 5;	Check existence.	PHP
let bar: Int = 'value'	let bar: String = 'value'	Fix type.	Swift
cin >> item cout << item;	cin >> item; cout << item;	Add semicolon.	C++
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
if val > 71 print('data')	if val > 71: print('data')	Colon missing after if.	Python
const y = 6; y = 62;	let y = 6; y = 62;	Cannot reassign const.	JavaScript
[62, 97, 20	[62, 97, 20]	Close bracket.	Ruby
<p>message <b>data</p></b>	<p>message <b>data</b></p>	Nest properly.	HTML
if bar = 34:	if bar == 34:	Use == for comparison.	Python
'45' + 90	45 + 90	Avoid string coercion.	JavaScript
jwt.sign({{id:58}}, 'key');	jwt.sign({{id:58}}, 'key', {{expiresIn:'15m'}});	Add expiration.	Node.js
'output' + 100	'output' + str(100)	Can't add int to string.	Python
if b = 75	if b == 75	Use ==.	MATLAB
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(48);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(48, () => console.log('listening'));	Add callback.	Node.js
[24, 100, 57	[24, 100, 57]	Close bracket.	Python
list[35]	if (length(list) >= 35) list[35]	Check length.	R
val b = 30; b = 76	var b = 30; b = 76	Use var for reassignment.	Scala
let num = 78; let num = 10;	let num = 78; num = 10;	Duplicate declaration.	JavaScript
[x*x for x in list if x > 20]	[x*x for x in list if x > 20]	Correct list comprehension.	Python
if (item = 40) {{}}	if (item === 40) {{}}	Use === for equality.	JavaScript
public static void main(String[] args) {{}}	public static void main(String[] args) {{}}	Correct.	Java
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
var x = 60;	var x = 60;	Correct.	Dart
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
let index = 47;	let index = 47;	Correct.	JavaScript
math.sqrt(40)	import math math.sqrt(40)	Import module first.	Python
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(63);	const http = require('http'); http.createServer((req,res) => res.end('output')).listen(63);	Correct.	Node.js
INSERT INTO orders VALUES ('message',72)	INSERT INTO orders (id, status) VALUES ('message',72);	Specify columns.	SQL
<div><p>info</div></p>	<div><p>info</p></div>	Nest properly.	HTML
for (result in data)	for (result of data)	for...in iterates keys.	JavaScript
let text1 = String::from("hello"); let s2 = text1; println!("{{}}", text1);	let text1 = String::from("hello"); let s2 = text1.clone(); println!("{{}}", text1);	Clone to avoid move.	Rust
let str = String::from("world"); let ref=&str; str.push_str("!");	let mut str = String::from("world"); let ref=&str; println!("{{}}", ref); str.push_str("!");	Cannot mutate while borrowed.	Rust
DELETE FROM items WHERE age=21	DELETE FROM items WHERE age=21;	Add semicolon.	SQL
int* user = nullptr; *user=5;	int* user = new int; *user=5;	Allocate memory.	C++
<ul><li>world<li>hello</ul>	<ul><li>world</li><li>hello</li></ul>	Close li.	HTML
{ "name": "result" }	{ "name": "result" }	Correct.	JSON
for (int i=0; i<59; i++) {{}}	for (int i=0; i<59; i++) {{}}	Correct.	Java
y > 89 & y < 3	y > 89 and y < 3	Use 'and' not '&'.	Python
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
echo 'world'	echo 'world';	Add semicolon.	PHP
if [ $foo = 87 ]; then	if [ "$foo" = 87 ]; then	Quote variable.	Shell
int[] list = new int[81]; list[81] = 5;	int[] list = new int[81]; if (81 < list.length) list[81] = 5;	Check bounds.	Java
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
list.forEach(function(c) {{ console.log(c); }})	list.forEach((c) => {{ console.log(c); }})	Arrow functions are cleaner.	JavaScript
println('world')	println("world")	Double quotes.	Scala
String item = 'result';	String item = "result";	Double quotes.	Java
items(33)	if length(items) >= 33, items(33), end	Check length.	MATLAB
h1 {{ font-size:43px color:red; }}	h1 {{ font-size:43px; color:red; }}	Add semicolon.	CSS
if (bar = 60) {}	if (bar == 60) {}	Use ==.	Dart
my @arr = (91,87,40);	my @arr = (91,87,40);	Correct.	Perl
{{"status":"message" "title":16}}	{{"status":"message", "title":16}}	Add comma.	JSON
raise 'hello'	raise Exception('hello')	Raise needs an exception class.	Python
<person age=15>	<person age="15">	Quote attribute.	XML
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
Order.save();	Order.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
handle	handle()	Add parentheses.	Kotlin
if (b = 23) {{}}	if (b == 23) {{}}	Use ==.	Kotlin
match c {{ 1 => {{}} }}	match c {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
if temp = 90	if temp == 90	Use ==.	Go
def process puts 'test' end	def process puts 'test' end	Correct.	Ruby
<br></br>	<br>	Self-closing.	HTML
// comment	/* comment */	Use /* */.	CSS
$list[77] = 5;	if (isset($list[77])) $list[77] = 5;	Check existence.	PHP
val = 36	val=36	No spaces.	Shell
String name = 'test';	String name = 'test';	Correct.	Dart
disp('output')	disp('output')	Correct.	MATLAB
jwt.sign({{id:80}}, 'key');	jwt.sign({{id:80}}, 'key', {{expiresIn:'1h'}});	Add expiration.	Node.js
UPDATE products SET id='output' WHERE email=16	UPDATE products SET id='output' WHERE email=16;	Add semicolon.	SQL
if (foo = 66)	if (foo == 66)	Use ==.	Scala
int data[44]; data[44]=5;	int data[44]; if(44<44){{}} else data[44]=5;	Bounds check.	C++
if data > 24 puts 'hello'	if data > 24 puts 'hello' end	Add 'end'.	Ruby
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
class = 'world'	class_name = 'world'	'class' is a keyword.	Python
#content {{ color: blue; }}	#content {{ color: blue; }}	Correct.	CSS
num == '61'	num === 61	Use strict equality.	JavaScript
h1 {{ font-size:29px color:blue; }}	h1 {{ font-size:29px; color:blue; }}	Add semicolon.	CSS
val count = 'message'	val count = "message"	Double quotes.	Kotlin
div {{ color=#fff; }}	div {{ color: #fff; }}	Use colon.	CSS
INSERT INTO items VALUES ('test',26)	INSERT INTO items (age, status) VALUES ('test',26);	Specify columns.	SQL
JOIN profiles ON users.id = profiles.id	JOIN profiles ON users.id = profiles.id	Correct.	SQL
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
function render() {{ return {{key:'hello'}} }}	function render() {{ return {{key:'hello'}}; }}	Return object on same line.	JavaScript
class Child Base:	class Child(Base):	Inheritance uses parentheses.	Python
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
'4' + 71	4 + 71	Avoid string coercion.	JavaScript
Write-Host 'message'	Write-Host 'message'	Correct.	PowerShell
x := 25	x := 25	Correct.	Go
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
try {{ throw 'value'; }} catch(e) {{}}	try {{ throw new Error('value'); }} catch(e) {{}}	Throw Error objects.	JavaScript
for (foo in data)	for (foo of data)	for...in iterates keys.	JavaScript
var temp int = 'result'	var temp string = 'result'	Type mismatch.	Go
if [ $val = 51 ]; then	if [ "$val" = 51 ]; then	Quote variable.	Shell
yield val	yield val	Correct yield.	Python
if z = 96	if z == 96	Use ==.	Ruby
arr[47]	if (length(arr) >= 47) arr[47]	Check length.	R
echo 'info'	echo 'info';	Add semicolon.	PHP
<table><tr><td>test<td>test</tr></table>	<table><tr><td>test</td><td>test</td></tr></table>	Close td.	HTML
object Item {{ def main(args: Array[String]) = println("value") }}	object Item {{ def main(args: Array[String]): Unit = println("value") }}	Add return type Unit.	Scala

my @arr = (36,5,38);

Correct.

Perl

$data[29] = 5;

if (isset($data[29])) $data[29] = 5;

Check existence.

PHP

let bar: Int = 'value'

let bar: String = 'value'

Fix type.

Swift

cin >> item cout << item;

cin >> item; cout << item;

Add semicolon.

C++

int x; System.out.println(x);

int x = 0; System.out.println(x);

Initialize variable.

Java

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

if val > 71 print('data')

if val > 71: print('data')

Colon missing after if.

Python

const y = 6; y = 62;

let y = 6; y = 62;

Cannot reassign const.

JavaScript

[62, 97, 20

[62, 97, 20]

Close bracket.

Ruby

<p>message <b>data</p></b>

<p>message <b>data</b></p>

Nest properly.

HTML

if bar = 34:

if bar == 34:

Use == for comparison.

Python

'45' + 90

45 + 90

Avoid string coercion.

JavaScript

jwt.sign({{id:58}}, 'key');

jwt.sign({{id:58}}, 'key', {{expiresIn:'15m'}});

Add expiration.

Node.js

'output' + 100

'output' + str(100)

Can't add int to string.

Python

if b = 75

if b == 75

Use ==.

MATLAB

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(48);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(48, () => console.log('listening'));

Add callback.

Node.js

[24, 100, 57

[24, 100, 57]

Close bracket.

Python

list[35]

if (length(list) >= 35) list[35]

Check length.

R

val b = 30; b = 76

var b = 30; b = 76

Use var for reassignment.

Scala

let num = 78; let num = 10;

let num = 78; num = 10;

Duplicate declaration.

JavaScript

[x*x for x in list if x > 20]

Correct list comprehension.

Python

if (item = 40) {{}}

if (item === 40) {{}}

Use === for equality.

JavaScript

public static void main(String[] args) {{}}

Correct.

Java

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

var x = 60;

Correct.

Dart

type MyType = string | number; let x: MyType = true;

type MyType = string | number; let x: MyType = 'hello';

Type not in union.

TypeScript

let index = 47;

Correct.

JavaScript

math.sqrt(40)

import math math.sqrt(40)

Import module first.

Python

const http = require('http'); http.createServer((req,res) => res.end('output')).listen(63);

Correct.

Node.js

INSERT INTO orders VALUES ('message',72)

INSERT INTO orders (id, status) VALUES ('message',72);

Specify columns.

SQL

Nest properly.

HTML

for (result in data)

for (result of data)

for...in iterates keys.

JavaScript

let text1 = String::from("hello"); let s2 = text1; println!("{{}}", text1);

let text1 = String::from("hello"); let s2 = text1.clone(); println!("{{}}", text1);

Clone to avoid move.

Rust

let str = String::from("world"); let ref=&str; str.push_str("!");

let mut str = String::from("world"); let ref=&str; println!("{{}}", ref); str.push_str("!");

Cannot mutate while borrowed.

Rust

DELETE FROM items WHERE age=21

DELETE FROM items WHERE age=21;

Add semicolon.

SQL

int* user = nullptr; *user=5;

int* user = new int; *user=5;

Allocate memory.

C++

<ul><li>world<li>hello</ul>

<ul><li>world</li><li>hello</li></ul>

Close li.

HTML

{ "name": "result" }

Correct.

JSON

for (int i=0; i<59; i++) {{}}

Correct.

Java

y > 89 & y < 3

y > 89 and y < 3

Use 'and' not '&'.

Python

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

echo 'world'

echo 'world';

Add semicolon.

PHP

if [ $foo = 87 ]; then

if [ "$foo" = 87 ]; then

Quote variable.

Shell

int[] list = new int[81]; list[81] = 5;

int[] list = new int[81]; if (81 < list.length) list[81] = 5;

Check bounds.

Java

x = 5; if x > 3, disp('large'), end

Correct.

MATLAB

list.forEach(function(c) {{ console.log(c); }})

list.forEach((c) => {{ console.log(c); }})

Arrow functions are cleaner.

JavaScript

println('world')

println("world")

Double quotes.

Scala

String item = 'result';

String item = "result";

Double quotes.

Java

items(33)

if length(items) >= 33, items(33), end

Check length.

MATLAB

h1 {{ font-size:43px color:red; }}

h1 {{ font-size:43px; color:red; }}

Add semicolon.

CSS

if (bar = 60) {}

if (bar == 60) {}

Use ==.

Dart

my @arr = (91,87,40);

Correct.

Perl

Add comma.

JSON

raise 'hello'

raise Exception('hello')

Raise needs an exception class.

Python

Quote attribute.

XML

@media screen {{ body {{}} }}

Correct.

CSS

Order.save();

Order.save().then(()=>{{}}).catch(err=>{{}});

Handle promise.

Node.js

handle

handle()

Add parentheses.

Kotlin

if (b = 23) {{}}

if (b == 23) {{}}

Use ==.

Kotlin

match c {{ 1 => {{}} }}

match c {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

if temp = 90

if temp == 90

Use ==.

Go

def process puts 'test' end

Correct.

Ruby

<br>

Self-closing.

HTML

// comment

/* comment */

Use /* */.

CSS

$list[77] = 5;

if (isset($list[77])) $list[77] = 5;

Check existence.

PHP

val = 36

val=36

No spaces.

Shell

String name = 'test';

Correct.

Dart

disp('output')

Correct.

MATLAB

jwt.sign({{id:80}}, 'key');

jwt.sign({{id:80}}, 'key', {{expiresIn:'1h'}});

Add expiration.

Node.js

UPDATE products SET id='output' WHERE email=16

UPDATE products SET id='output' WHERE email=16;

Add semicolon.

SQL

if (foo = 66)

if (foo == 66)

Use ==.

Scala

int data[44]; data[44]=5;

int data[44]; if(44<44){{}} else data[44]=5;

Bounds check.

C++

if data > 24 puts 'hello'

if data > 24 puts 'hello' end

Add 'end'.

Ruby

x <- 5; if (x > 3) print('large')

Correct.

R

class = 'world'

class_name = 'world'

'class' is a keyword.

Python

#content {{ color: blue; }}

Correct.

CSS

num == '61'

num === 61

Use strict equality.

JavaScript

h1 {{ font-size:29px color:blue; }}

h1 {{ font-size:29px; color:blue; }}

Add semicolon.

CSS

val count = 'message'

val count = "message"

Double quotes.

Kotlin

div {{ color=#fff; }}

div {{ color: #fff; }}

Use colon.

CSS

INSERT INTO items VALUES ('test',26)

INSERT INTO items (age, status) VALUES ('test',26);

Specify columns.

SQL

JOIN profiles ON users.id = profiles.id

Correct.

SQL

int main() {{ return 0; }}

Correct.

C++

function render() {{ return {{key:'hello'}} }}

function render() {{ return {{key:'hello'}}; }}

Return object on same line.

JavaScript

class Child Base:

class Child(Base):

Inheritance uses parentheses.

Python

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

'4' + 71

4 + 71

Avoid string coercion.

JavaScript

Write-Host 'message'

Correct.

PowerShell

x := 25

Correct.

Go

x = 5; if x > 3, disp('large'), end

Correct.

MATLAB

try {{ throw 'value'; }} catch(e) {{}}

try {{ throw new Error('value'); }} catch(e) {{}}

Throw Error objects.

JavaScript

for (foo in data)

for (foo of data)

for...in iterates keys.

JavaScript

var temp int = 'result'

var temp string = 'result'

Type mismatch.

Go

if [ $val = 51 ]; then

if [ "$val" = 51 ]; then

Quote variable.

Shell

yield val

Correct yield.

Python

if z = 96

if z == 96

Use ==.

Ruby

arr[47]

if (length(arr) >= 47) arr[47]

Check length.

R

echo 'info'

echo 'info';

Add semicolon.

PHP

Close td.

HTML

object Item {{ def main(args: Array[String]) = println("value") }}

object Item {{ def main(args: Array[String]): Unit = println("value") }}

Add return type Unit.

Scala