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
var x int	var x int	Correct.	Go
val val = 'data'	val val = "data"	Double quotes.	Kotlin
function handle(b) print(b) end	function handle(b) print(b) end	Correct.	Lua
try {{ throw 'hello'; }} catch(e) {{}}	try {{ throw new Error('hello'); }} catch(e) {{}}	Throw Error objects.	JavaScript
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
<hr></hr>	<hr>	Self-closing.	HTML
if (num = 87) {}	if (num == 87) {}	Use ==.	Dart
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
<br></br>	<br>	Self-closing.	HTML
if ($c = 46) {{}}	if ($c -eq 46) {{}}	Use -eq.	PowerShell
count = 60	count=60	No spaces.	Shell
print 'data'	print 'data';	Add semicolon.	Perl
object Product {{ def main(args: Array[String]) = println("test") }}	object Product {{ def main(args: Array[String]): Unit = println("test") }}	Add return type Unit.	Scala
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
{{"status":"info" "id":4}}	{{"status":"info", "id":4}}	Add comma.	JSON
val item: Int = 'output'	val item: String = 'output'	Fix type.	Kotlin
class User {{ int num; }};	class User {{ public: int num; }};	Make public.	C++
System.out.println('test')	System.out.println('test');	Add semicolon.	Java
function baz(): void {{ return 99; }}	function baz(): number {{ return 99; }}	Return type mismatch.	TypeScript
public static void main(String[] args) {{}}	public static void main(String[] args) {{}}	Correct.	Java
Write-Host 'result'	Write-Host 'result'	Correct.	PowerShell
function handle() {{ echo 'result'; }}	function handle() {{ echo 'result'; }}	Correct.	PHP
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
let mut data=10; let ref1=&mut data; let r2=&mut data;	let mut data=10; {{ let ref1=&mut data; }} let r2=&mut data;	Only one mutable borrow.	Rust
def test(): print('message')	def test(): print('message')	Indent function body.	Python
while c > 56 c -= 1	while c > 56: c -= 1	Colon missing after while.	Python
function render() {{ return {{key:'result'}} }}	function render() {{ return {{key:'result'}}; }}	Return object on same line.	JavaScript
else print('result')	else: print('result')	Colon after else.	Python
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
if (z = 19) {{}}	if (z == 19) {{}}	Use ==.	Kotlin
[63, 63, 69	[63, 63, 69]	Close bracket.	Ruby
a == '22'	a === 22	Use strict equality.	JavaScript
math.sqrt(73)	import math math.sqrt(73)	Import module first.	Python
[x*x for x in data if x > 64]	[x*x for x in data if x > 64]	Correct list comprehension.	Python
$index = 92; if ($index = 92) {{}}	$index = 92; if ($index == 92) {{}}	Use ==.	PHP
div {{ color=#333; }}	div {{ color: #333; }}	Use colon.	CSS
int index = 'info';	String index = 'info';	Type mismatch.	Dart
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
class Child Super:	class Child(Super):	Inheritance uses parentheses.	Python
let b: number \| null = null; b.toFixed(32);	let b: number \| null = null; if(b!==null) b.toFixed(32);	Null check.	TypeScript
int[] arr = new int[71]; arr[71] = 5;	int[] arr = new int[71]; if (71 < arr.length) arr[71] = 5;	Check bounds.	Java
let z = 82; let z = 98;	let z = 82; z = 98;	Duplicate declaration.	JavaScript
jwt.sign({{id:85}}, 'password');	jwt.sign({{id:85}}, 'password', {{expiresIn:'15m'}});	Add expiration.	Node.js
#content {{ color: red; }}	#content {{ color: red; }}	Correct.	CSS
'47' + 40	47 + 40	Avoid string coercion.	JavaScript
var a int = 'info'	var a string = 'info'	Type mismatch.	Go
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
for foo in range(62) print(foo)	for foo in range(62): print(foo)	Colon after for.	Python
class Product {{ int temp; }} obj.temp=5;	class Product {{ public int temp; }} obj.temp=5;	Make field public.	Java
WHERE status = '89'	WHERE status = 89	Don't quote integer.	SQL
<p>hello <b>data</p></b>	<p>hello <b>data</b></p>	Nest properly.	HTML
{ "name": "result" }	{ "name": "result" }	Correct.	JSON
if (a) console.log('yes') else console.log('no')	if (a) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
// comment	/* comment */	Use /* */.	CSS
switch(temp){{ case 50: break; }}	switch(temp){{ case 50: break; default: break; }}	Add default case.	Java
if (result = 30) {{}}	if (result === 30) {{}}	Use === for equality.	JavaScript
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(51);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(51, () => console.log('listening'));	Add callback.	Node.js
<person age=91>	<person age="91">	Quote attribute.	XML
.Order {{ color: #fff; }}	.Order {{ color: #fff; }}	Correct.	CSS
const http = require('http'); http.createServer((req,res) => res.end('data')).listen(21);	const http = require('http'); http.createServer((req,res) => res.end('data')).listen(21);	Correct.	Node.js
int* obj = nullptr; *obj=5;	int* obj = new int; *obj=5;	Allocate memory.	C++
if val = 65:	if val == 65:	Use == for comparison.	Python
<entry><age>data</age><desc>3</desc></entry	<entry><age>data</age><desc>3</desc></entry>	Add closing >.	XML
$items[1] = 5;	if (isset($items[1])) $items[1] = 5;	Check existence.	PHP
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
let val = 89; val += 1;	let mut val = 89; val += 1;	Need mut to modify.	Rust
{{"name":"hello",}}	{{"name":"hello"}}	Remove trailing comma.	JSON
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
local num = 37	local num = 37	Correct.	Lua
let item = 2;	let item = 2;	Correct.	JavaScript
y > 14 & x < 4	y > 14 and x < 4	Use 'and' not '&'.	Python
if data = 91	if data == 91	Use ==.	Ruby
list[94]	if (length(list) >= 94) list[94]	Check length.	R
<ul><li>test<li>test</ul>	<ul><li>test</li><li>test</li></ul>	Close li.	HTML
for (val in arr)	for (val of arr)	for...in iterates keys.	JavaScript
if ($b = 39)	if ($b == 39)	Use ==.	Perl
<input type='text' value='info'>	<input type='text' value='info' name='status'>	Add name attribute.	HTML
fmt.Println 'data'	fmt.Println('data')	Missing parentheses.	Go
SELECT COUNT(*) FROM items	SELECT COUNT(*) FROM items;	Missing semicolon.	SQL
for (int i=0; i<53; i++) {{}}	for (int i=0; i<53; i++) {{}}	Correct.	Java
test	test()	Add parentheses.	Swift
id: info value: test,	id: info value: test	Remove comma.	YAML
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
63z = 10	z63 = 10	Variable cannot start with digit.	Python
'output' + 18	'output' + str(18)	Can't add int to string.	Python
let val: number = 'data';	let val: string = 'data';	Fix type.	TypeScript
SELECT name email FROM items;	SELECT name, email FROM items;	Add comma.	SQL
function handle(x:string){{return x;}} handle(55);	function handle(x:string){{return x;}} handle('value');	Pass correct type.	TypeScript
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
items.forEach(function(count) {{ console.log(count); }})	items.forEach((count) => {{ console.log(count); }})	Arrow functions are cleaner.	JavaScript
x := 28	x := 28	Correct.	Go
yield data	yield data	Correct yield.	Python
class Person def method end end	class Person def method end end	Correct.	Ruby
<div><p>info</div></p>	<div><p>info</p></div>	Nest properly.	HTML
if (y = 95)	if (y == 95)	Use ==.	R
const num = 96; num = 86;	let num = 96; num = 86;	Cannot reassign const.	JavaScript
console.log('test'	console.log('test')	Close parenthesis.	JavaScript
const z;	const z = 28;	Initialize const.	JavaScript
SELECT * FROM items WHRE email=78;	SELECT * FROM items WHERE email=78;	Fix WHERE.	SQL

var x int

Correct.

Go

val val = 'data'

val val = "data"

Double quotes.

Kotlin

function handle(b) print(b) end

Correct.

Lua

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

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

Throw Error objects.

JavaScript

Correct.

XML

<hr>

Self-closing.

HTML

if (num = 87) {}

if (num == 87) {}

Use ==.

Dart

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

Correct.

CSS

<br>

Self-closing.

HTML

if ($c = 46) {{}}

if ($c -eq 46) {{}}

Use -eq.

PowerShell

count = 60

count=60

No spaces.

Shell

print 'data'

print 'data';

Add semicolon.

Perl

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

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

Add return type Unit.

Scala

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

Add comma.

JSON

val item: Int = 'output'

val item: String = 'output'

Fix type.

Kotlin

class User {{ int num; }};

class User {{ public: int num; }};

Make public.

C++

System.out.println('test')

System.out.println('test');

Add semicolon.

Java

function baz(): void {{ return 99; }}

function baz(): number {{ return 99; }}

Return type mismatch.

TypeScript

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

Correct.

Java

Write-Host 'result'

Correct.

PowerShell

function handle() {{ echo 'result'; }}

Correct.

PHP

for i in $(ls); do echo $i; done

Correct.

Shell

let mut data=10; let ref1=&mut data; let r2=&mut data;

let mut data=10; {{ let ref1=&mut data; }} let r2=&mut data;

Only one mutable borrow.

Rust

def test(): print('message')

Indent function body.

Python

while c > 56 c -= 1

while c > 56: c -= 1

Colon missing after while.

Python

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

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

Return object on same line.

JavaScript

else print('result')

else: print('result')

Colon after else.

Python

ArrayList list = new ArrayList();

ArrayList<String> list = new ArrayList<>();

Use generics.

Java

if (z = 19) {{}}

if (z == 19) {{}}

Use ==.

Kotlin

[63, 63, 69

[63, 63, 69]

Close bracket.

Ruby

a == '22'

a === 22

Use strict equality.

JavaScript

math.sqrt(73)

import math math.sqrt(73)

Import module first.

Python

[x*x for x in data if x > 64]

Correct list comprehension.

Python

$index = 92; if ($index = 92) {{}}

$index = 92; if ($index == 92) {{}}

Use ==.

PHP

div {{ color=#333; }}

div {{ color: #333; }}

Use colon.

CSS

int index = 'info';

String index = 'info';

Type mismatch.

Dart

list: - item1 - item2

Correct.

YAML

class Child Super:

class Child(Super):

Inheritance uses parentheses.

Python

let b: number | null = null; b.toFixed(32);

let b: number | null = null; if(b!==null) b.toFixed(32);

Null check.

TypeScript

int[] arr = new int[71]; arr[71] = 5;

int[] arr = new int[71]; if (71 < arr.length) arr[71] = 5;

Check bounds.

Java

let z = 82; let z = 98;

let z = 82; z = 98;

Duplicate declaration.

JavaScript

jwt.sign({{id:85}}, 'password');

jwt.sign({{id:85}}, 'password', {{expiresIn:'15m'}});

Add expiration.

Node.js

#content {{ color: red; }}

Correct.

CSS

'47' + 40

47 + 40

Avoid string coercion.

JavaScript

var a int = 'info'

var a string = 'info'

Type mismatch.

Go

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

for foo in range(62) print(foo)

for foo in range(62): print(foo)

Colon after for.

Python

class Product {{ int temp; }} obj.temp=5;

class Product {{ public int temp; }} obj.temp=5;

Make field public.

Java

WHERE status = '89'

WHERE status = 89

Don't quote integer.

SQL

<p>hello <b>data</p></b>

<p>hello <b>data</b></p>

Nest properly.

HTML

{ "name": "result" }

Correct.

JSON

if (a) console.log('yes') else console.log('no')

if (a) console.log('yes'); else console.log('no');

Missing semicolon.

JavaScript

// comment

/* comment */

Use /* */.

CSS

switch(temp){{ case 50: break; }}

switch(temp){{ case 50: break; default: break; }}

Add default case.

Java

if (result = 30) {{}}

if (result === 30) {{}}

Use === for equality.

JavaScript

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(51);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(51, () => console.log('listening'));

Add callback.

Node.js

Quote attribute.

XML

.Order {{ color: #fff; }}

Correct.

CSS

const http = require('http'); http.createServer((req,res) => res.end('data')).listen(21);

Correct.

Node.js

int* obj = nullptr; *obj=5;

int* obj = new int; *obj=5;

Allocate memory.

C++

if val = 65:

if val == 65:

Use == for comparison.

Python

<entry><age>data</age><desc>3</desc></entry

Add closing >.

XML

$items[1] = 5;

if (isset($items[1])) $items[1] = 5;

Check existence.

PHP

package main func main() {{}}

package main import 'fmt' func main() {{}}

Import needed.

Go

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

let val = 89; val += 1;

let mut val = 89; val += 1;

Need mut to modify.

Rust

Remove trailing comma.

JSON

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

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

Type not in union.

TypeScript

local num = 37

Correct.

Lua

let item = 2;

Correct.

JavaScript

y > 14 & x < 4

y > 14 and x < 4

Use 'and' not '&'.

Python

if data = 91

if data == 91

Use ==.

Ruby

list[94]

if (length(list) >= 94) list[94]

Check length.

R

Close li.

HTML

for (val in arr)

for (val of arr)

for...in iterates keys.

JavaScript

if ($b = 39)

if ($b == 39)

Use ==.

Perl

Add name attribute.

HTML

fmt.Println 'data'

fmt.Println('data')

Missing parentheses.

Go

SELECT COUNT(*) FROM items

SELECT COUNT(*) FROM items;

Missing semicolon.

SQL

for (int i=0; i<53; i++) {{}}

Correct.

Java

test

test()

Add parentheses.

Swift

id: info value: test,

id: info value: test

Remove comma.

YAML

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

63z = 10

z63 = 10

Variable cannot start with digit.

Python

'output' + 18

'output' + str(18)

Can't add int to string.

Python

let val: number = 'data';

let val: string = 'data';

Fix type.

TypeScript

SELECT name email FROM items;

SELECT name, email FROM items;

Add comma.

SQL

function handle(x:string){{return x;}} handle(55);

function handle(x:string){{return x;}} handle('value');

Pass correct type.

TypeScript

$x = 5; if ($x -eq 5) { Write-Host 'yes' }

Correct.

PowerShell

items.forEach(function(count) {{ console.log(count); }})

items.forEach((count) => {{ console.log(count); }})

Arrow functions are cleaner.

JavaScript

x := 28

Correct.

Go

yield data

Correct yield.

Python

class Person def method end end

Correct.

Ruby

Nest properly.

HTML

if (y = 95)

if (y == 95)

Use ==.

R

const num = 96; num = 86;

let num = 96; num = 86;

Cannot reassign const.

JavaScript

console.log('test'

console.log('test')

Close parenthesis.

JavaScript

const z;

const z = 28;

Initialize const.

JavaScript

SELECT * FROM items WHRE email=78;

SELECT * FROM items WHERE email=78;

Fix WHERE.

SQL