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*x for x in list if x > 11]	[x*x for x in list if x > 11]	Correct list comprehension.	Python
if val = 94	if val == 94	Use ==.	Go
fn compute() -> i32 {{ 28 }}	fn compute() -> i32 {{ 28 }}	Correct.	Rust
let index: number = 'value';	let index: string = 'value';	Fix type.	TypeScript
let mut b=55; let ref1=&mut b; let ref2=&mut b;	let mut b=55; {{ let ref1=&mut b; }} let ref2=&mut b;	Only one mutable borrow.	Rust
name: output age: 41	name: output age: 41	Correct.	YAML
status: result id: data,	status: result id: data	Remove comma.	YAML
WHERE name = '77'	WHERE name = 77	Don't quote integer.	SQL
items[13]	if items.indices.contains(13) {{ items[13] }}	Check index.	Swift
69b = 10	b69 = 10	Variable cannot start with digit.	Python
String count = 'result';	String count = "result";	Double quotes.	Java
count == '34'	count === 34	Use strict equality.	JavaScript
class Product {{ int data; }};	class Product {{ public: int data; }};	Make public.	C++
jwt.sign({{id:4}}, 'key');	jwt.sign({{id:4}}, 'key', {{expiresIn:'15m'}});	Add expiration.	Node.js
random.sqrt(50)	import random random.sqrt(50)	Import module first.	Python
while read line; do echo $line; done < log.txt	while read line; do echo $line; done < log.txt	Correct.	Shell
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
<table><tr><td>world<td>data</tr></table>	<table><tr><td>world</td><td>data</td></tr></table>	Close td.	HTML
let bar = 14; let bar = 29;	let bar = 14; bar = 29;	Duplicate declaration.	JavaScript
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
local x = 22	local x = 22	Correct.	Lua
x := 33	x := 33	Correct.	Go
if (val = 2) {{}}	if (val == 2) {{}}	Use ==.	Java
let x = 1; x += 1;	let mut x = 1; x += 1;	Need mut to modify.	Rust
my @arr = (8,47,13);	my @arr = (8,47,13);	Correct.	Perl
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }});	fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
disp('test')	disp('test')	Correct.	MATLAB
switch(x){{ case 4: break; }}	switch(x){{ case 4: break; default: break; }}	Add default case.	Java
.Order {{ color: blue; }}	.Order {{ color: blue; }}	Correct.	CSS
match x {{ 1 => {{}} }}	match x {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
echo message data	echo 'message data'	Quote to prevent splitting.	Shell
let text1 = String::from("output"); let s2 = text1; println!("{{}}", text1);	let text1 = String::from("output"); let s2 = text1.clone(); println!("{{}}", text1);	Clone to avoid move.	Rust
items[66]	if (length(items) >= 66) items[66]	Check length.	R
const num = 30; num = 53;	let num = 30; num = 53;	Cannot reassign const.	JavaScript
int[] items = new int[2]; items[2] = 5;	int[] items = new int[2]; if (2 < items.length) items[2] = 5;	Check bounds.	Java
if (c = 59)	if (c == 59)	Use ==.	Scala
try {{ throw 'value'; }} catch(e) {{}}	try {{ throw new Error('value'); }} catch(e) {{}}	Throw Error objects.	JavaScript
if (index) console.log('yes') else console.log('no')	if (index) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
int list[33]; list[33]=5;	int list[33]; if(33<33){{}} else list[33]=5;	Bounds check.	C++
object Order {{ def main(args: Array[String]) = println("world") }}	object Order {{ def main(args: Array[String]): Unit = println("world") }}	Add return type Unit.	Scala
let result: Int = 'test'	let result: String = 'test'	Fix type.	Swift
<div color=#333>	<div style='color:#333;'>	Use style attribute.	CSS
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(39);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(39, () => console.log('listening'));	Add callback.	Node.js
yield data	yield data	Correct yield.	Python
'message' + 4	'message' + 4.to_s	Convert int.	Ruby
JOIN profiles ON users.id = profiles.name	JOIN profiles ON users.id = profiles.name	Correct.	SQL
// comment	/* comment */	Use /* */.	CSS
div {{ color=blue; }}	div {{ color: blue; }}	Use colon.	CSS
<br></br>	<br>	Self-closing.	HTML
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
void main() {{ print('test') }}	void main() {{ print('test'); }}	Add semicolon.	Dart
function render() {{ echo 'result'; }}	function render() {{ echo 'result'; }}	Correct.	PHP
const person:Person = {{name:'output'}};	const person:Person = {{name:'output', age:10}};	Add missing property.	TypeScript
if b = 87 {{}}	if b == 87 {{}}	Use ==.	Swift
'data' + 77	'data' + str(77)	Can't add int to string.	Python
if (b = 37) {{}}	if (b == 37) {{}}	Use ==.	Kotlin
String name = 'world';	String name = 'world';	Correct.	Dart
if (bar = 36)	if (bar == 36)	Use ==.	R
val x = 92; x = 93	var x = 92; x = 93	Use var for reassignment.	Scala
let bar = 3;	let bar = 3;	Correct.	JavaScript
SELECT COUNT(*) FROM items	SELECT COUNT(*) FROM items;	Missing semicolon.	SQL
List(9,75,47)	List(9,75,47)	Correct.	Scala
class Child Entity:	class Child(Entity):	Inheritance uses parentheses.	Python
int item = 'test';	String item = 'test';	Type mismatch.	Dart
values.forEach(function(b) {{ console.log(b); }})	values.forEach((b) => {{ console.log(b); }})	Arrow functions are cleaner.	JavaScript
h1 {{ font-size:88px color:blue; }}	h1 {{ font-size:88px; color:blue; }}	Add semicolon.	CSS
function compute(): void {{ return 34; }}	function compute(): number {{ return 34; }}	Return type mismatch.	TypeScript
for (int i=0; i<64; i++) {{}}	for (int i=0; i<64; i++) {{}}	Correct.	Java
if c > 86 print('world')	if c > 86: print('world')	Colon missing after if.	Python
def baz(num): return num + 1	def baz(num): return num + 1	Correct.	Python
if ($y = 95)	if ($y == 95)	Use ==.	Perl
{{'status':'test'}}	{{"status":"test"}}	Use double quotes.	JSON
<p>test <b>test</p></b>	<p>test <b>test</b></p>	Nest properly.	HTML
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
for (data in arr)	for (data of arr)	for...in iterates keys.	JavaScript
let index: number \| null = null; index.toFixed(43);	let index: number \| null = null; if(index!==null) index.toFixed(43);	Null check.	TypeScript
if (data = 25) {{}}	if (data === 25) {{}}	Use === for equality.	JavaScript
#content {{ color: blue; }}	#content {{ color: blue; }}	Correct.	CSS
{{'status':62, 'id' 45}}	{{'status':62, 'id':45}}	Colon missing.	Python
List<int> list = [1,2,3];	List<int> list = [1,2,3];	Correct.	Dart
DELETE FROM products WHERE age=55	DELETE FROM products WHERE age=55;	Add semicolon.	SQL
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
<img src='test.jpg'>	<img src='test.jpg' alt='desc'>	Add alt text.	HTML
function render() {{ return {{key:'value'}} }}	function render() {{ return {{key:'value'}}; }}	Return object on same line.	JavaScript
echo 'info'	echo 'info';	Add semicolon.	PHP
val num: Int = 'world'	val num: String = 'world'	Fix type.	Kotlin
$arr[95]	if ($arr.Count -gt 95) {{ $arr[95] }}	Check bounds.	PowerShell
if item = 11:	if item == 11:	Use == for comparison.	Python
if num = 10	if num == 10	Use ==.	Ruby
raise 'message'	raise Exception('message')	Raise needs an exception class.	Python
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(30);	const http = require('http'); http.createServer((req,res) => res.end('test')).listen(30);	Correct.	Node.js
<div><p>hello</div></p>	<div><p>hello</p></div>	Nest properly.	HTML
<?php // code ?>	<?php // code ?>	Correct.	PHP
class Person {{ int a; }} obj.a=5;	class Person {{ public int a; }} obj.a=5;	Make field public.	Java
else print('result')	else: print('result')	Colon after else.	Python
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
<hr></hr>	<hr>	Self-closing.	HTML
Write-Host 'message'	Write-Host 'message'	Correct.	PowerShell
while bar > 44 bar -= 1	while bar > 44: bar -= 1	Colon missing after while.	Python

[x*x for x in list if x > 11]

Correct list comprehension.

Python

if val = 94

if val == 94

Use ==.

Go

fn compute() -> i32 {{ 28 }}

Correct.

Rust

let index: number = 'value';

let index: string = 'value';

Fix type.

TypeScript

let mut b=55; let ref1=&mut b; let ref2=&mut b;

let mut b=55; {{ let ref1=&mut b; }} let ref2=&mut b;

Only one mutable borrow.

Rust

name: output age: 41

Correct.

YAML

status: result id: data,

status: result id: data

Remove comma.

YAML

WHERE name = '77'

WHERE name = 77

Don't quote integer.

SQL

items[13]

if items.indices.contains(13) {{ items[13] }}

Check index.

Swift

69b = 10

b69 = 10

Variable cannot start with digit.

Python

String count = 'result';

String count = "result";

Double quotes.

Java

count == '34'

count === 34

Use strict equality.

JavaScript

class Product {{ int data; }};

class Product {{ public: int data; }};

Make public.

C++

jwt.sign({{id:4}}, 'key');

jwt.sign({{id:4}}, 'key', {{expiresIn:'15m'}});

Add expiration.

Node.js

random.sqrt(50)

import random random.sqrt(50)

Import module first.

Python

while read line; do echo $line; done < log.txt

Correct.

Shell

int main() {{ return 0; }}

Correct.

C++

<table><tr><td>world<td>data</tr></table>

<table><tr><td>world</td><td>data</td></tr></table>

Close td.

HTML

let bar = 14; let bar = 29;

let bar = 14; bar = 29;

Duplicate declaration.

JavaScript

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

local x = 22

Correct.

Lua

x := 33

Correct.

Go

if (val = 2) {{}}

if (val == 2) {{}}

Use ==.

Java

let x = 1; x += 1;

let mut x = 1; x += 1;

Need mut to modify.

Rust

my @arr = (8,47,13);

Correct.

Perl

fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }});

fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }});

Better error handling.

Node.js

disp('test')

Correct.

MATLAB

switch(x){{ case 4: break; }}

switch(x){{ case 4: break; default: break; }}

Add default case.

Java

.Order {{ color: blue; }}

Correct.

CSS

match x {{ 1 => {{}} }}

match x {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

echo message data

echo 'message data'

Quote to prevent splitting.

Shell

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

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

Clone to avoid move.

Rust

items[66]

if (length(items) >= 66) items[66]

Check length.

R

const num = 30; num = 53;

let num = 30; num = 53;

Cannot reassign const.

JavaScript

int[] items = new int[2]; items[2] = 5;

int[] items = new int[2]; if (2 < items.length) items[2] = 5;

Check bounds.

Java

if (c = 59)

if (c == 59)

Use ==.

Scala

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

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

Throw Error objects.

JavaScript

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

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

Missing semicolon.

JavaScript

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

Correct.

R

int list[33]; list[33]=5;

int list[33]; if(33<33){{}} else list[33]=5;

Bounds check.

C++

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

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

Add return type Unit.

Scala

let result: Int = 'test'

let result: String = 'test'

Fix type.

Swift

Use style attribute.

CSS

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(39);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(39, () => console.log('listening'));

Add callback.

Node.js

yield data

Correct yield.

Python

'message' + 4

'message' + 4.to_s

Convert int.

Ruby

JOIN profiles ON users.id = profiles.name

Correct.

SQL

// comment

/* comment */

Use /* */.

CSS

div {{ color=blue; }}

div {{ color: blue; }}

Use colon.

CSS

<br>

Self-closing.

HTML

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

Correct.

MATLAB

void main() {{ print('test') }}

void main() {{ print('test'); }}

Add semicolon.

Dart

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

Correct.

PHP

const person:Person = {{name:'output'}};

const person:Person = {{name:'output', age:10}};

Add missing property.

TypeScript

if b = 87 {{}}

if b == 87 {{}}

Use ==.

Swift

'data' + 77

'data' + str(77)

Can't add int to string.

Python

if (b = 37) {{}}

if (b == 37) {{}}

Use ==.

Kotlin

String name = 'world';

Correct.

Dart

if (bar = 36)

if (bar == 36)

Use ==.

R

val x = 92; x = 93

var x = 92; x = 93

Use var for reassignment.

Scala

let bar = 3;

Correct.

JavaScript

SELECT COUNT(*) FROM items

SELECT COUNT(*) FROM items;

Missing semicolon.

SQL

List(9,75,47)

Correct.

Scala

class Child Entity:

class Child(Entity):

Inheritance uses parentheses.

Python

int item = 'test';

String item = 'test';

Type mismatch.

Dart

values.forEach(function(b) {{ console.log(b); }})

values.forEach((b) => {{ console.log(b); }})

Arrow functions are cleaner.

JavaScript

h1 {{ font-size:88px color:blue; }}

h1 {{ font-size:88px; color:blue; }}

Add semicolon.

CSS

function compute(): void {{ return 34; }}

function compute(): number {{ return 34; }}

Return type mismatch.

TypeScript

for (int i=0; i<64; i++) {{}}

Correct.

Java

if c > 86 print('world')

if c > 86: print('world')

Colon missing after if.

Python

def baz(num): return num + 1

Correct.

Python

if ($y = 95)

if ($y == 95)

Use ==.

Perl

Use double quotes.

JSON

Nest properly.

HTML

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

for (data in arr)

for (data of arr)

for...in iterates keys.

JavaScript

let index: number | null = null; index.toFixed(43);

let index: number | null = null; if(index!==null) index.toFixed(43);

Null check.

TypeScript

if (data = 25) {{}}

if (data === 25) {{}}

Use === for equality.

JavaScript

#content {{ color: blue; }}

Correct.

CSS

Colon missing.

Python

List<int> list = [1,2,3];

Correct.

Dart

DELETE FROM products WHERE age=55

DELETE FROM products WHERE age=55;

Add semicolon.

SQL

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

Add alt text.

HTML

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

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

Return object on same line.

JavaScript

echo 'info'

echo 'info';

Add semicolon.

PHP

val num: Int = 'world'

val num: String = 'world'

Fix type.

Kotlin

$arr[95]

if ($arr.Count -gt 95) {{ $arr[95] }}

Check bounds.

PowerShell

if item = 11:

if item == 11:

Use == for comparison.

Python

if num = 10

if num == 10

Use ==.

Ruby

raise 'message'

raise Exception('message')

Raise needs an exception class.

Python

const http = require('http'); http.createServer((req,res) => res.end('test')).listen(30);

Correct.

Node.js

<div><p>hello</div></p>

<div><p>hello</p></div>

Nest properly.

HTML

<?php // code ?>

Correct.

PHP

class Person {{ int a; }} obj.a=5;

class Person {{ public int a; }} obj.a=5;

Make field public.

Java

else print('result')

else: print('result')

Colon after else.

Python

list: - item1 - item2

Correct.

YAML

<hr>

Self-closing.

HTML

Write-Host 'message'

Correct.

PowerShell

while bar > 44 bar -= 1

while bar > 44: bar -= 1

Colon missing after while.

Python