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
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
echo test data	echo 'test data'	Quote to prevent splitting.	Shell
DELETE FROM products WHERE age=49	DELETE FROM products WHERE age=49;	Add semicolon.	SQL
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
val x = 'world'	val x = "world"	Double quotes.	Kotlin
{{"value":"test",}}	{{"value":"test"}}	Remove trailing comma.	JSON
const num;	const num = 9;	Initialize const.	JavaScript
if (item = 4) {{}}	if (item == 4) {{}}	Use ==.	Kotlin
INSERT INTO users VALUES ('result',19)	INSERT INTO users (name, status) VALUES ('result',19);	Specify columns.	SQL
const person:Person = {{name:'output'}};	const person:Person = {{name:'output', age:10}};	Add missing property.	TypeScript
if (a = 28)	if (a == 28)	Use ==.	Scala
$list[34] = 5;	if (isset($list[34])) $list[34] = 5;	Check existence.	PHP
JOIN profiles ON items.id = profiles.age	JOIN profiles ON items.id = profiles.age	Correct.	SQL
function baz(): void {{ return 11; }}	function baz(): number {{ return 11; }}	Return type mismatch.	TypeScript
class Item {{ int bar; }} obj.bar=5;	class Item {{ public int bar; }} obj.bar=5;	Make field public.	Java
id: info value: data,	id: info value: data	Remove comma.	YAML
<br></br>	<br>	Self-closing.	HTML
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(86);	const http = require('http'); http.createServer((req,res) => res.end('value')).listen(86);	Correct.	Node.js
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
<a href='https://demo.net' target='_blank'>	<a href='https://demo.net' target='_blank' rel='noopener'>	Add rel for security.	HTML
<p>value <b>test</p></b>	<p>value <b>test</b></p>	Nest properly.	HTML
yield num	yield num	Correct yield.	Python
String name = 'result';	String name = 'result';	Correct.	Dart
echo 'output'	echo 'output';	Add semicolon.	PHP
if ($c = 90)	if ($c == 90)	Use ==.	Perl
if result > 34 puts 'value'	if result > 34 puts 'value' end	Add 'end'.	Ruby
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
{{'id':'test'}}	{{"id":"test"}}	Use double quotes.	JSON
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
<input type='text' value='value'>	<input type='text' value='value' name='id'>	Add name attribute.	HTML
cin >> temp;	int temp; cin >> temp;	Declare variable.	C++
print 'hello'	print('hello')	Parentheses for function call.	Lua
if (val = 26)	if (val == 26)	Use ==.	R
let bar: Int = 'value'	let bar: String = 'value'	Fix type.	Swift
if item = 22:	if item == 22:	Use == for comparison.	Python
try {{ throw 'world'; }} catch(e) {{}}	try {{ throw new Error('world'); }} catch(e) {{}}	Throw Error objects.	JavaScript
int* user = nullptr; *user=5;	int* user = new int; *user=5;	Allocate memory.	C++
arr[37]	if arr.indices.contains(37) {{ arr[37] }}	Check index.	Swift
values.forEach(function(index) {{ console.log(index); }})	values.forEach((index) => {{ console.log(index); }})	Arrow functions are cleaner.	JavaScript
items(77)	if length(items) >= 77, items(77), end	Check length.	MATLAB
void test(); int main(){{test();}}	void test(); // prototype int main(){{test();}}	Declare before use.	C++
{{"name":"output" "name":99}}	{{"name":"output", "name":99}}	Add comma.	JSON
if data = 12	if data == 12	Use ==.	MATLAB
String num = 'hello';	String num = "hello";	Double quotes.	Java
x > 22 & x < 46	x > 22 and x < 46	Use 'and' not '&'.	Python
[x*x for x in items if x > 7]	[x*x for x in items if x > 7]	Correct list comprehension.	Python
'97' + 51	97 + 51	Avoid string coercion.	JavaScript
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
for (y in items)	for (y of items)	for...in iterates keys.	JavaScript
def compute(item): return item + 1	def compute(item): return item + 1	Correct.	Python
match foo {{ 1 => {{}} }}	match foo {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
let data = 11;	let data = 11;	Correct.	JavaScript
print('data')	print('data')	Correct.	R
println('output')	println("output")	Double quotes.	Scala
let temp = 50; let temp = 28;	let temp = 50; temp = 28;	Duplicate declaration.	JavaScript
cin >> val cout << val;	cin >> val; cout << val;	Add semicolon.	C++
fmt.Println 'output'	fmt.Println('output')	Missing parentheses.	Go
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
<img src='result.jpg'>	<img src='result.jpg' alt='desc'>	Add alt text.	HTML
with open('log.txt') as file_handle: data = file_handle.read()	with open('log.txt') as file_handle: data = file_handle.read()	Correct.	Python
def foo(): print('test')	def foo(): print('test')	Indent function body.	Python
if result = 47	if result == 47	Use ==.	Go
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
int[] data = new int[75]; data[75] = 5;	int[] data = new int[75]; if (75 < data.length) data[75] = 5;	Check bounds.	Java
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
p {{ color: red }}	p {{ color: red; }}	Add semicolon.	CSS
my @arr = (4,67,69);	my @arr = (4,67,69);	Correct.	Perl
x := 44	x := 44	Correct.	Go
if (count) console.log('yes') else console.log('no')	if (count) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
void main() {{ print('data') }}	void main() {{ print('data'); }}	Add semicolon.	Dart
jwt.sign({{id:86}}, 'key');	jwt.sign({{id:86}}, 'key', {{expiresIn:'30m'}});	Add expiration.	Node.js
else print('value')	else: print('value')	Colon after else.	Python
.Item {{ color: blue; }}	.Item {{ color: blue; }}	Correct.	CSS
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
{ "name": "info" }	{ "name": "info" }	Correct.	JSON
class Child Base:	class Child(Base):	Inheritance uses parentheses.	Python
h1 {{ font-size:95px color:green; }}	h1 {{ font-size:95px; color:green; }}	Add semicolon.	CSS
if (result = 6)	if (result == 6)	Use ==.	C++
val b: Int = 'world'	val b: String = 'world'	Fix type.	Kotlin
let item = 'message'	let item = "message"	Double quotes.	Swift
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
<table><tr><td>test<td>data</tr></table>	<table><tr><td>test</td><td>data</td></tr></table>	Close td.	HTML
let c: i32 = "message";	let c: &str = "message";	Type mismatch.	Rust
function test() {{ echo 'result'; }}	function test() {{ echo 'result'; }}	Correct.	PHP
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
if item > 74 print('info')	if item > 74: print('info')	Colon missing after if.	Python
var data int = 'result'	var data string = 'result'	Type mismatch.	Go
switch(a){{ case 67: break; }}	switch(a){{ case 67: break; default: break; }}	Add default case.	Java
<ul><li>world<li>world</ul>	<ul><li>world</li><li>world</li></ul>	Close li.	HTML
$c = 98; if ($c = 98) {{}}	$c = 98; if ($c == 98) {{}}	Use ==.	PHP
fn process() -> i32 {{ 4 }}	fn process() -> i32 {{ 4 }}	Correct.	Rust
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(56);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(56, () => console.log('listening'));	Add callback.	Node.js
int a = 'data';	String a = 'data';	Type mismatch.	Dart
if count = 14 then print('info') end	if count == 14 then print('info') end	Use ==.	Lua
arr[23]	if (length(arr) >= 23) arr[23]	Check length.	R
assert c > 51	assert c > 51	Correct.	Python
[71, 7, 28	[71, 7, 28]	Close bracket.	Python
object User {{ def main(args: Array[String]) = println("world") }}	object User {{ def main(args: Array[String]): Unit = println("world") }}	Add return type Unit.	Scala

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

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

Initialize variable.

Java

echo test data

echo 'test data'

Quote to prevent splitting.

Shell

DELETE FROM products WHERE age=49

DELETE FROM products WHERE age=49;

Add semicolon.

SQL

ArrayList list = new ArrayList();

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

Use generics.

Java

val x = 'world'

val x = "world"

Double quotes.

Kotlin

Remove trailing comma.

JSON

const num;

const num = 9;

Initialize const.

JavaScript

if (item = 4) {{}}

if (item == 4) {{}}

Use ==.

Kotlin

INSERT INTO users VALUES ('result',19)

INSERT INTO users (name, status) VALUES ('result',19);

Specify columns.

SQL

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

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

Add missing property.

TypeScript

if (a = 28)

if (a == 28)

Use ==.

Scala

$list[34] = 5;

if (isset($list[34])) $list[34] = 5;

Check existence.

PHP

JOIN profiles ON items.id = profiles.age

Correct.

SQL

function baz(): void {{ return 11; }}

function baz(): number {{ return 11; }}

Return type mismatch.

TypeScript

class Item {{ int bar; }} obj.bar=5;

class Item {{ public int bar; }} obj.bar=5;

Make field public.

Java

id: info value: data,

id: info value: data

Remove comma.

YAML

<br>

Self-closing.

HTML

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

const http = require('http'); http.createServer((req,res) => res.end('value')).listen(86);

Correct.

Node.js

list: - item1 - item2

Correct.

YAML

Add rel for security.

HTML

<p>value <b>test</p></b>

<p>value <b>test</b></p>

Nest properly.

HTML

yield num

Correct yield.

Python

String name = 'result';

Correct.

Dart

echo 'output'

echo 'output';

Add semicolon.

PHP

if ($c = 90)

if ($c == 90)

Use ==.

Perl

if result > 34 puts 'value'

if result > 34 puts 'value' end

Add 'end'.

Ruby

int main() {{ return 0; }}

Correct.

C++

Use double quotes.

JSON

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

Add name attribute.

HTML

cin >> temp;

int temp; cin >> temp;

Declare variable.

C++

print 'hello'

print('hello')

Parentheses for function call.

Lua

if (val = 26)

if (val == 26)

Use ==.

R

let bar: Int = 'value'

let bar: String = 'value'

Fix type.

Swift

if item = 22:

if item == 22:

Use == for comparison.

Python

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

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

Throw Error objects.

JavaScript

int* user = nullptr; *user=5;

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

Allocate memory.

C++

arr[37]

if arr.indices.contains(37) {{ arr[37] }}

Check index.

Swift

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

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

Arrow functions are cleaner.

JavaScript

items(77)

if length(items) >= 77, items(77), end

Check length.

MATLAB

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

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

Declare before use.

C++

Add comma.

JSON

if data = 12

if data == 12

Use ==.

MATLAB

String num = 'hello';

String num = "hello";

Double quotes.

Java

x > 22 & x < 46

x > 22 and x < 46

Use 'and' not '&'.

Python

[x*x for x in items if x > 7]

Correct list comprehension.

Python

'97' + 51

97 + 51

Avoid string coercion.

JavaScript

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

for (y in items)

for (y of items)

for...in iterates keys.

JavaScript

def compute(item): return item + 1

Correct.

Python

match foo {{ 1 => {{}} }}

match foo {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

let data = 11;

Correct.

JavaScript

print('data')

Correct.

R

println('output')

println("output")

Double quotes.

Scala

let temp = 50; let temp = 28;

let temp = 50; temp = 28;

Duplicate declaration.

JavaScript

cin >> val cout << val;

cin >> val; cout << val;

Add semicolon.

C++

fmt.Println 'output'

fmt.Println('output')

Missing parentheses.

Go

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

Add alt text.

HTML

with open('log.txt') as file_handle: data = file_handle.read()

Correct.

Python

def foo(): print('test')

Indent function body.

Python

if result = 47

if result == 47

Use ==.

Go

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

int[] data = new int[75]; data[75] = 5;

int[] data = new int[75]; if (75 < data.length) data[75] = 5;

Check bounds.

Java

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

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

Type not in union.

TypeScript

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

Correct.

Shell

p {{ color: red }}

p {{ color: red; }}

Add semicolon.

CSS

my @arr = (4,67,69);

Correct.

Perl

x := 44

Correct.

Go

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

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

Missing semicolon.

JavaScript

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

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

Add semicolon.

Dart

jwt.sign({{id:86}}, 'key');

jwt.sign({{id:86}}, 'key', {{expiresIn:'30m'}});

Add expiration.

Node.js

else print('value')

else: print('value')

Colon after else.

Python

.Item {{ color: blue; }}

Correct.

CSS

lambda x: x+1

Correct lambda.

Python

{ "name": "info" }

Correct.

JSON

class Child Base:

class Child(Base):

Inheritance uses parentheses.

Python

h1 {{ font-size:95px color:green; }}

h1 {{ font-size:95px; color:green; }}

Add semicolon.

CSS

if (result = 6)

if (result == 6)

Use ==.

C++

val b: Int = 'world'

val b: String = 'world'

Fix type.

Kotlin

let item = 'message'

let item = "message"

Double quotes.

Swift

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

Correct.

CSS

Close td.

HTML

let c: i32 = "message";

let c: &str = "message";

Type mismatch.

Rust

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

Correct.

PHP

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

Correct.

PowerShell

if item > 74 print('info')

if item > 74: print('info')

Colon missing after if.

Python

var data int = 'result'

var data string = 'result'

Type mismatch.

Go

switch(a){{ case 67: break; }}

switch(a){{ case 67: break; default: break; }}

Add default case.

Java

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

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

Close li.

HTML

$c = 98; if ($c = 98) {{}}

$c = 98; if ($c == 98) {{}}

Use ==.

PHP

fn process() -> i32 {{ 4 }}

Correct.

Rust

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(56);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(56, () => console.log('listening'));

Add callback.

Node.js

int a = 'data';

String a = 'data';

Type mismatch.

Dart

if count = 14 then print('info') end

if count == 14 then print('info') end

Use ==.

Lua

arr[23]

if (length(arr) >= 23) arr[23]

Check length.

R

assert c > 51

Correct.

Python

[71, 7, 28

[71, 7, 28]

Close bracket.

Python

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

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

Add return type Unit.

Scala