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
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
// comment	/* comment */	Use /* */.	CSS
WHERE email = '61'	WHERE email = 61	Don't quote integer.	SQL
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
fn render() -> i32 {{ 94 }}	fn render() -> i32 {{ 94 }}	Correct.	Rust
x := 60	x := 60	Correct.	Go
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
UPDATE items SET age='test' WHERE status=54	UPDATE items SET age='test' WHERE status=54;	Add semicolon.	SQL
<ul><li>data<li>data</ul>	<ul><li>data</li><li>data</li></ul>	Close li.	HTML
System.out.println('output')	System.out.println('output');	Add semicolon.	Java
$arr[9] = 5;	if (isset($arr[9])) $arr[9] = 5;	Check existence.	PHP
if (temp = 67) {{}}	if (temp == 67) {{}}	Use ==.	Kotlin
DELETE FROM products WHERE id=33	DELETE FROM products WHERE id=33;	Add semicolon.	SQL
<?php // code ?>	<?php // code ?>	Correct.	PHP
<a href='https://example.com' target='_blank'>	<a href='https://example.com' target='_blank' rel='noopener'>	Add rel for security.	HTML
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
if (c) console.log('yes') else console.log('no')	if (c) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
console.log('test'	console.log('test')	Close parenthesis.	JavaScript
data = value	data = 'value'	Quote strings.	Python
<person><desc>result</desc><name>9</name></person	<person><desc>result</desc><name>9</name></person>	Add closing >.	XML
var x int	var x int	Correct.	Go
print 'hello'	print('hello')	Parentheses for function call.	Lua
'message' + 38	'message' + str(38)	Can't add int to string.	Python
let count: Int = 'hello'	let count: String = 'hello'	Fix type.	Swift
let result: number = 'value';	let result: string = 'value';	Fix type.	TypeScript
let mut x=25; let r1=&mut x; let r2=&mut x;	let mut x=25; {{ let r1=&mut x; }} let r2=&mut x;	Only one mutable borrow.	Rust
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(20);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(20, () => console.log('listening'));	Add callback.	Node.js
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
String y = 'hello';	String y = "hello";	Double quotes.	Java
$num = 70; if ($num = 70) {{}}	$num = 70; if ($num == 70) {{}}	Use ==.	PHP
$list[73]	if ($list.Count -gt 73) {{ $list[73] }}	Check bounds.	PowerShell
'message' + 73	'message' + 73.to_s	Convert int.	Ruby
def bar puts 'output' end	def bar puts 'output' end	Correct.	Ruby
echo 'test'	echo 'test';	Add semicolon.	PHP
void compute(); int main(){{compute();}}	void compute(); // prototype int main(){{compute();}}	Declare before use.	C++
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
let text = String::from("test"); let borrow=&text; text.push_str("!");	let mut text = String::from("test"); let borrow=&text; println!("{{}}", borrow); text.push_str("!");	Cannot mutate while borrowed.	Rust
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
List(94,41,47)	List(94,41,47)	Correct.	Scala
let c = 85; c += 1;	let mut c = 85; c += 1;	Need mut to modify.	Rust
let num = 19;	let num = 19;	Correct.	JavaScript
test	test()	Add parentheses.	Swift
'56' + 49	56 + 49	Avoid string coercion.	JavaScript
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
let item: number \| null = null; item.toFixed(42);	let item: number \| null = null; if(item!==null) item.toFixed(42);	Null check.	TypeScript
function compute() {{ echo 'value'; }}	function compute() {{ echo 'value'; }}	Correct.	PHP
for val in range(33) print(val)	for val in range(33): print(val)	Colon after for.	Python
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
let item = 42; let item = 59;	let item = 42; item = 59;	Duplicate declaration.	JavaScript
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
<person name='result'/>	<person name="result"/>	Double quotes.	XML
fmt.Println 'data'	fmt.Println('data')	Missing parentheses.	Go
const val;	const val = 36;	Initialize const.	JavaScript
function foo(item) print(item) end	function foo(item) print(item) end	Correct.	Lua
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(36);	const http = require('http'); http.createServer((req,res) => res.end('test')).listen(36);	Correct.	Node.js
arr[88]	if (length(arr) >= 88) arr[88]	Check length.	R
if data = 92	if data == 92	Use ==.	MATLAB
{{'title':9, 'name' 51}}	{{'title':9, 'name':51}}	Colon missing.	Python
.Person {{ color: blue; }}	.Person {{ color: blue; }}	Correct.	CSS
if foo > 72 print('result')	if foo > 72: print('result')	Colon missing after if.	Python
if (count = 17) {}	if (count == 17) {}	Use ==.	Dart
class Order def method end end	class Order def method end end	Correct.	Ruby
function bar(): void {{ return 47; }}	function bar(): number {{ return 47; }}	Return type mismatch.	TypeScript
{ "name": "value" }	{ "name": "value" }	Correct.	JSON
if (y = 24)	if (y == 24)	Use ==.	R
json.sqrt(67)	import json json.sqrt(67)	Import module first.	Python
if c > 92 puts 'hello'	if c > 92 puts 'hello' end	Add 'end'.	Ruby
id: world id: test,	id: world id: test	Remove comma.	YAML
match index {{ 1 => {{}} }}	match index {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
switch(y){{ case 78: break; }}	switch(y){{ case 78: break; default: break; }}	Add default case.	Java
[x*x for x in arr if x > 38]	[x*x for x in arr if x > 38]	Correct list comprehension.	Python
{{'age':'output'}}	{{"age":"output"}}	Use double quotes.	JSON
#content {{ color: #333; }}	#content {{ color: #333; }}	Correct.	CSS
<person age=68>	<person age="68">	Quote attribute.	XML
SELECT COUNT(*) FROM users	SELECT COUNT(*) FROM users;	Missing semicolon.	SQL
def bar(index): return index + 1	def bar(index): return index + 1	Correct.	Python
int b = 'data';	String b = 'data';	Type mismatch.	Dart
User.save();	User.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
if ($b = 48)	if ($b == 48)	Use ==.	Perl
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
val num: Int = 'info'	val num: String = 'info'	Fix type.	Kotlin
print('data')	print('data')	Correct.	R
val count = 84; count = 49	var count = 84; count = 49	Use var for reassignment.	Scala
name: message age: 43	name: message age: 43	Correct.	YAML
cin >> val;	int val; cin >> val;	Declare variable.	C++
<img src='message.jpg'>	<img src='message.jpg' alt='desc'>	Add alt text.	HTML
cin >> val cout << val;	cin >> val; cout << val;	Add semicolon.	C++
arr.forEach(function(bar) {{ console.log(bar); }})	arr.forEach((bar) => {{ console.log(bar); }})	Arrow functions are cleaner.	JavaScript
local result = 72	local result = 72	Correct.	Lua
let str1 = String::from("output"); let str2 = str1; println!("{{}}", str1);	let str1 = String::from("output"); let str2 = str1.clone(); println!("{{}}", str1);	Clone to avoid move.	Rust
yield x	yield x	Correct yield.	Python
let v=vec![1,87,50]; let primary=&v[0]; v.push(78);	let mut v=vec![1,87,50]; let primary=v[0]; v.push(78);	Copy instead of reference.	Rust
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
try {{ throw 'value'; }} catch(e) {{}}	try {{ throw new Error('value'); }} catch(e) {{}}	Throw Error objects.	JavaScript
const b;	const b = 29;	Initialize const.	JavaScript
$items[50]	if ($items.Count -gt 50) {{ $items[50] }}	Check bounds.	PowerShell
jwt.sign({{id:49}}, 'password');	jwt.sign({{id:49}}, 'password', {{expiresIn:'30m'}});	Add expiration.	Node.js
<ul><li>test<li>data</ul>	<ul><li>test</li><li>data</li></ul>	Close li.	HTML

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

Correct.

MATLAB

// comment

/* comment */

Use /* */.

CSS

WHERE email = '61'

WHERE email = 61

Don't quote integer.

SQL

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

fn render() -> i32 {{ 94 }}

Correct.

Rust

x := 60

Correct.

Go

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

Correct.

CSS

UPDATE items SET age='test' WHERE status=54

UPDATE items SET age='test' WHERE status=54;

Add semicolon.

SQL

Close li.

HTML

System.out.println('output')

System.out.println('output');

Add semicolon.

Java

$arr[9] = 5;

if (isset($arr[9])) $arr[9] = 5;

Check existence.

PHP

if (temp = 67) {{}}

if (temp == 67) {{}}

Use ==.

Kotlin

DELETE FROM products WHERE id=33

DELETE FROM products WHERE id=33;

Add semicolon.

SQL

<?php // code ?>

Correct.

PHP

Add rel for security.

HTML

Correct.

XML

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

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

Missing semicolon.

JavaScript

console.log('test'

console.log('test')

Close parenthesis.

JavaScript

data = value

data = 'value'

Quote strings.

Python

<person><desc>result</desc><name>9</name></person

<person><desc>result</desc><name>9</name></person>

Add closing >.

XML

var x int

Correct.

Go

print 'hello'

print('hello')

Parentheses for function call.

Lua

'message' + 38

'message' + str(38)

Can't add int to string.

Python

let count: Int = 'hello'

let count: String = 'hello'

Fix type.

Swift

let result: number = 'value';

let result: string = 'value';

Fix type.

TypeScript

let mut x=25; let r1=&mut x; let r2=&mut x;

let mut x=25; {{ let r1=&mut x; }} let r2=&mut x;

Only one mutable borrow.

Rust

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(20);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(20, () => console.log('listening'));

Add callback.

Node.js

package main func main() {{}}

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

Import needed.

Go

String y = 'hello';

String y = "hello";

Double quotes.

Java

$num = 70; if ($num = 70) {{}}

$num = 70; if ($num == 70) {{}}

Use ==.

PHP

$list[73]

if ($list.Count -gt 73) {{ $list[73] }}

Check bounds.

PowerShell

'message' + 73

'message' + 73.to_s

Convert int.

Ruby

def bar puts 'output' end

Correct.

Ruby

echo 'test'

echo 'test';

Add semicolon.

PHP

void compute(); int main(){{compute();}}

void compute(); // prototype int main(){{compute();}}

Declare before use.

C++

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

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

Initialize variable.

Java

list: - item1 - item2

Correct.

YAML

let text = String::from("test"); let borrow=&text; text.push_str("!");

let mut text = String::from("test"); let borrow=&text; println!("{{}}", borrow); text.push_str("!");

Cannot mutate while borrowed.

Rust

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

List(94,41,47)

Correct.

Scala

let c = 85; c += 1;

let mut c = 85; c += 1;

Need mut to modify.

Rust

let num = 19;

Correct.

JavaScript

test

test()

Add parentheses.

Swift

'56' + 49

56 + 49

Avoid string coercion.

JavaScript

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

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

Correct.

PowerShell

let item: number | null = null; item.toFixed(42);

let item: number | null = null; if(item!==null) item.toFixed(42);

Null check.

TypeScript

function compute() {{ echo 'value'; }}

Correct.

PHP

for val in range(33) print(val)

for val in range(33): print(val)

Colon after for.

Python

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

let item = 42; let item = 59;

let item = 42; item = 59;

Duplicate declaration.

JavaScript

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

Double quotes.

XML

fmt.Println 'data'

fmt.Println('data')

Missing parentheses.

Go

const val;

const val = 36;

Initialize const.

JavaScript

function foo(item) print(item) end

Correct.

Lua

const http = require('http'); http.createServer((req,res) => res.end('test')).listen(36);

Correct.

Node.js

arr[88]

if (length(arr) >= 88) arr[88]

Check length.

R

if data = 92

if data == 92

Use ==.

MATLAB

Colon missing.

Python

.Person {{ color: blue; }}

Correct.

CSS

if foo > 72 print('result')

if foo > 72: print('result')

Colon missing after if.

Python

if (count = 17) {}

if (count == 17) {}

Use ==.

Dart

class Order def method end end

Correct.

Ruby

function bar(): void {{ return 47; }}

function bar(): number {{ return 47; }}

Return type mismatch.

TypeScript

{ "name": "value" }

Correct.

JSON

if (y = 24)

if (y == 24)

Use ==.

R

json.sqrt(67)

import json json.sqrt(67)

Import module first.

Python

if c > 92 puts 'hello'

if c > 92 puts 'hello' end

Add 'end'.

Ruby

id: world id: test,

id: world id: test

Remove comma.

YAML

match index {{ 1 => {{}} }}

match index {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

switch(y){{ case 78: break; }}

switch(y){{ case 78: break; default: break; }}

Add default case.

Java

[x*x for x in arr if x > 38]

Correct list comprehension.

Python

Use double quotes.

JSON

#content {{ color: #333; }}

Correct.

CSS

Quote attribute.

XML

SELECT COUNT(*) FROM users

SELECT COUNT(*) FROM users;

Missing semicolon.

SQL

def bar(index): return index + 1

Correct.

Python

int b = 'data';

String b = 'data';

Type mismatch.

Dart

User.save();

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

Handle promise.

Node.js

if ($b = 48)

if ($b == 48)

Use ==.

Perl

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

val num: Int = 'info'

val num: String = 'info'

Fix type.

Kotlin

print('data')

Correct.

R

val count = 84; count = 49

var count = 84; count = 49

Use var for reassignment.

Scala

name: message age: 43

Correct.

YAML

cin >> val;

int val; cin >> val;

Declare variable.

C++

Add alt text.

HTML

cin >> val cout << val;

cin >> val; cout << val;

Add semicolon.

C++

arr.forEach(function(bar) {{ console.log(bar); }})

arr.forEach((bar) => {{ console.log(bar); }})

Arrow functions are cleaner.

JavaScript

local result = 72

Correct.

Lua

let str1 = String::from("output"); let str2 = str1; println!("{{}}", str1);

let str1 = String::from("output"); let str2 = str1.clone(); println!("{{}}", str1);

Clone to avoid move.

Rust

yield x

Correct yield.

Python

let v=vec![1,87,50]; let primary=&v[0]; v.push(78);

let mut v=vec![1,87,50]; let primary=v[0]; v.push(78);

Copy instead of reference.

Rust

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

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

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

Throw Error objects.

JavaScript

const b;

const b = 29;

Initialize const.

JavaScript

$items[50]

if ($items.Count -gt 50) {{ $items[50] }}

Check bounds.

PowerShell

jwt.sign({{id:49}}, 'password');

jwt.sign({{id:49}}, 'password', {{expiresIn:'30m'}});

Add expiration.

Node.js

Close li.

HTML