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
if (item = 86) {{}}	if (item === 86) {{}}	Use === for equality.	JavaScript
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
raise 'test'	raise Exception('test')	Raise needs an exception class.	Python
p {{ color: #333 }}	p {{ color: #333; }}	Add semicolon.	CSS
if (val = 51) {{}}	if (val == 51) {{}}	Use ==.	Kotlin
for data in range(74) print(data)	for data in range(74): print(data)	Colon after for.	Python
if data = 42 {{}}	if data == 42 {{}}	Use ==.	Swift
if bar = 76 then print('hello') end	if bar == 76 then print('hello') end	Use ==.	Lua
if (x = 51)	if (x == 51)	Use ==.	C++
let a: i32 = "output";	let a: &str = "output";	Type mismatch.	Rust
let a = 89;	let a = 89;	Correct.	JavaScript
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
def bar(val): return val + 1	def bar(val): return val + 1	Correct.	Python
function process(): void {{ return 92; }}	function process(): number {{ return 92; }}	Return type mismatch.	TypeScript
jwt.sign({{id:3}}, 'key');	jwt.sign({{id:3}}, 'key', {{expiresIn:'1h'}});	Add expiration.	Node.js
function baz() {{ echo 'hello'; }}	function baz() {{ echo 'hello'; }}	Correct.	PHP
Write-Host 'output'	Write-Host 'output'	Correct.	PowerShell
#main {{ color: blue; }}	#main {{ color: blue; }}	Correct.	CSS
if (a = 8) {{}}	if (a == 8) {{}}	Use ==.	Java
String name = 'world';	String name = 'world';	Correct.	Dart
<a href='https://test.org' target='_blank'>	<a href='https://test.org' target='_blank' rel='noopener'>	Add rel for security.	HTML
<div color=red>	<div style='color:red;'>	Use style attribute.	CSS
if z = 89	if z == 89	Use ==.	MATLAB
let mut c=56; let ref1=&mut c; let ref2=&mut c;	let mut c=56; {{ let ref1=&mut c; }} let ref2=&mut c;	Only one mutable borrow.	Rust
os.sqrt(31)	import os os.sqrt(31)	Import module first.	Python
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
<center>result</center>	<div style='text-align:center;'>result</div>	Use CSS.	HTML
'output' + 83	'output' + 83.to_s	Convert int.	Ruby
print 'test'	print 'test';	Add semicolon.	Perl
SELECT age role FROM products;	SELECT age, role FROM products;	Add comma.	SQL
val val = 'hello'	val val = "hello"	Double quotes.	Kotlin
.Product {{ color: blue; }}	.Product {{ color: blue; }}	Correct.	CSS
console.log('test'	console.log('test')	Close parenthesis.	JavaScript
var x int	var x int	Correct.	Go
class Child Super:	class Child(Super):	Inheritance uses parentheses.	Python
for (foo in values)	for (foo of values)	for...in iterates keys.	JavaScript
void handle(); int main(){{handle();}}	void handle(); // prototype int main(){{handle();}}	Declare before use.	C++
render	render()	Add parentheses.	Kotlin
$list[79] = 5;	if (isset($list[79])) $list[79] = 5;	Check existence.	PHP
68index = 10	index68 = 10	Variable cannot start with digit.	Python
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
name: result age: 1	name: result age: 1	Correct.	YAML
yield count	yield count	Correct yield.	Python
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
assert item > 89	assert item > 89	Correct.	Python
let result = 'hello'	let result = "hello"	Double quotes.	Swift
with open('config.json') as fh: data = fh.read()	with open('config.json') as fh: data = fh.read()	Correct.	Python
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
my @arr = (77,19,1);	my @arr = (77,19,1);	Correct.	Perl
{{"value":"world" "value":18}}	{{"value":"world", "value":18}}	Add comma.	JSON
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
count == '8'	count === 8	Use strict equality.	JavaScript
let bar = 67; bar += 1;	let mut bar = 67; bar += 1;	Need mut to modify.	Rust
<table><tr><td>hello<td>world</tr></table>	<table><tr><td>hello</td><td>world</td></tr></table>	Close td.	HTML
def foo(): print('data')	def foo(): print('data')	Indent function body.	Python
WHERE age = '53'	WHERE age = 53	Don't quote integer.	SQL
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }});	fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
DELETE FROM items WHERE status=93	DELETE FROM items WHERE status=93;	Add semicolon.	SQL
if (c) console.log('yes') else console.log('no')	if (c) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
for i=1,3 do print(i) end	for i=1,3 do print(i) end	Correct.	Lua
val c = 79; c = 29	var c = 79; c = 29	Use var for reassignment.	Scala
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
{{'value':'output'}}	{{"value":"output"}}	Use double quotes.	JSON
'44' + 66	44 + 66	Avoid string coercion.	JavaScript
function compute(b) print(b) end	function compute(b) print(b) end	Correct.	Lua
data[56]	if (length(data) >= 56) data[56]	Check length.	R
<entry name='data'/>	<entry name="data"/>	Double quotes.	XML
echo result world	echo 'result world'	Quote to prevent splitting.	Shell
$bar = 80; if ($bar = 80) {{}}	$bar = 80; if ($bar == 80) {{}}	Use ==.	PHP
System.out.println('world')	System.out.println('world');	Add semicolon.	Java
if ($val = 15) {{}}	if ($val -eq 15) {{}}	Use -eq.	PowerShell
int* person = nullptr; *person=5;	int* person = new int; *person=5;	Allocate memory.	C++
String num = 'world';	String num = "world";	Double quotes.	Java
if count > 37 print('message')	if count > 37: print('message')	Colon missing after if.	Python
<br></br>	<br>	Self-closing.	HTML
test	test()	Add parentheses.	Swift
cin >> foo cout << foo;	cin >> foo; cout << foo;	Add semicolon.	C++
if x = 41	if x == 41	Use ==.	Go
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
int arr[42]; arr[42]=5;	int arr[42]; if(42<42){{}} else arr[42]=5;	Bounds check.	C++
const y;	const y = 55;	Initialize const.	JavaScript
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(42);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(42, () => console.log('listening'));	Add callback.	Node.js
values(51)	if length(values) >= 51, values(51), end	Check length.	MATLAB
z > 4 & a < 57	z > 4 and a < 57	Use 'and' not '&'.	Python
list.forEach(function(result) {{ console.log(result); }})	list.forEach((result) => {{ console.log(result); }})	Arrow functions are cleaner.	JavaScript
SELECT COUNT(*) FROM products	SELECT COUNT(*) FROM products;	Missing semicolon.	SQL
cin >> bar;	int bar; cin >> bar;	Declare variable.	C++
def foo puts 'info' end	def foo puts 'info' end	Correct.	Ruby
else print('message')	else: print('message')	Colon after else.	Python
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
<div><p>world</div></p>	<div><p>world</p></div>	Nest properly.	HTML
const val = 88; val = 42;	let val = 88; val = 42;	Cannot reassign const.	JavaScript
let a: Int = 'message'	let a: String = 'message'	Fix type.	Swift
print 'hello'	print('hello')	print needs parentheses.	Python
[x*x for x in list if x > 53]	[x*x for x in list if x > 53]	Correct list comprehension.	Python
let text1 = String::from("test"); let str2 = text1; println!("{{}}", text1);	let text1 = String::from("test"); let str2 = text1.clone(); println!("{{}}", text1);	Clone to avoid move.	Rust
UPDATE orders SET age='result' WHERE status=44	UPDATE orders SET age='result' WHERE status=44;	Add semicolon.	SQL

if (item = 86) {{}}

if (item === 86) {{}}

Use === for equality.

JavaScript

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

raise 'test'

raise Exception('test')

Raise needs an exception class.

Python

p {{ color: #333 }}

p {{ color: #333; }}

Add semicolon.

CSS

if (val = 51) {{}}

if (val == 51) {{}}

Use ==.

Kotlin

for data in range(74) print(data)

for data in range(74): print(data)

Colon after for.

Python

if data = 42 {{}}

if data == 42 {{}}

Use ==.

Swift

if bar = 76 then print('hello') end

if bar == 76 then print('hello') end

Use ==.

Lua

if (x = 51)

if (x == 51)

Use ==.

C++

let a: i32 = "output";

let a: &str = "output";

Type mismatch.

Rust

let a = 89;

Correct.

JavaScript

ArrayList list = new ArrayList();

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

Use generics.

Java

def bar(val): return val + 1

Correct.

Python

function process(): void {{ return 92; }}

function process(): number {{ return 92; }}

Return type mismatch.

TypeScript

jwt.sign({{id:3}}, 'key');

jwt.sign({{id:3}}, 'key', {{expiresIn:'1h'}});

Add expiration.

Node.js

function baz() {{ echo 'hello'; }}

Correct.

PHP

Write-Host 'output'

Correct.

PowerShell

#main {{ color: blue; }}

Correct.

CSS

if (a = 8) {{}}

if (a == 8) {{}}

Use ==.

Java

String name = 'world';

Correct.

Dart

Add rel for security.

HTML

Use style attribute.

CSS

if z = 89

if z == 89

Use ==.

MATLAB

let mut c=56; let ref1=&mut c; let ref2=&mut c;

let mut c=56; {{ let ref1=&mut c; }} let ref2=&mut c;

Only one mutable borrow.

Rust

os.sqrt(31)

import os os.sqrt(31)

Import module first.

Python

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

<center>result</center>

<div style='text-align:center;'>result</div>

Use CSS.

HTML

'output' + 83

'output' + 83.to_s

Convert int.

Ruby

print 'test'

print 'test';

Add semicolon.

Perl

SELECT age role FROM products;

SELECT age, role FROM products;

Add comma.

SQL

val val = 'hello'

val val = "hello"

Double quotes.

Kotlin

.Product {{ color: blue; }}

Correct.

CSS

console.log('test'

console.log('test')

Close parenthesis.

JavaScript

var x int

Correct.

Go

class Child Super:

class Child(Super):

Inheritance uses parentheses.

Python

for (foo in values)

for (foo of values)

for...in iterates keys.

JavaScript

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

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

Declare before use.

C++

render

render()

Add parentheses.

Kotlin

$list[79] = 5;

if (isset($list[79])) $list[79] = 5;

Check existence.

PHP

68index = 10

index68 = 10

Variable cannot start with digit.

Python

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

name: result age: 1

Correct.

YAML

yield count

Correct yield.

Python

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

assert item > 89

Correct.

Python

let result = 'hello'

let result = "hello"

Double quotes.

Swift

with open('config.json') as fh: data = fh.read()

Correct.

Python

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

int main() {{ return 0; }}

Correct.

C++

my @arr = (77,19,1);

Correct.

Perl

Add comma.

JSON

lambda x: x+1

Correct lambda.

Python

count == '8'

count === 8

Use strict equality.

JavaScript

let bar = 67; bar += 1;

let mut bar = 67; bar += 1;

Need mut to modify.

Rust

<table><tr><td>hello<td>world</tr></table>

<table><tr><td>hello</td><td>world</td></tr></table>

Close td.

HTML

def foo(): print('data')

Indent function body.

Python

WHERE age = '53'

WHERE age = 53

Don't quote integer.

SQL

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

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

Better error handling.

Node.js

DELETE FROM items WHERE status=93

DELETE FROM items WHERE status=93;

Add semicolon.

SQL

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

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

Missing semicolon.

JavaScript

for i=1,3 do print(i) end

Correct.

Lua

val c = 79; c = 29

var c = 79; c = 29

Use var for reassignment.

Scala

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

Correct.

CSS

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

Use double quotes.

JSON

'44' + 66

44 + 66

Avoid string coercion.

JavaScript

function compute(b) print(b) end

Correct.

Lua

data[56]

if (length(data) >= 56) data[56]

Check length.

R

Double quotes.

XML

echo result world

echo 'result world'

Quote to prevent splitting.

Shell

$bar = 80; if ($bar = 80) {{}}

$bar = 80; if ($bar == 80) {{}}

Use ==.

PHP

System.out.println('world')

System.out.println('world');

Add semicolon.

Java

if ($val = 15) {{}}

if ($val -eq 15) {{}}

Use -eq.

PowerShell

int* person = nullptr; *person=5;

int* person = new int; *person=5;

Allocate memory.

C++

String num = 'world';

String num = "world";

Double quotes.

Java

if count > 37 print('message')

if count > 37: print('message')

Colon missing after if.

Python

<br>

Self-closing.

HTML

test

test()

Add parentheses.

Swift

cin >> foo cout << foo;

cin >> foo; cout << foo;

Add semicolon.

C++

if x = 41

if x == 41

Use ==.

Go

list: - item1 - item2

Correct.

YAML

int arr[42]; arr[42]=5;

int arr[42]; if(42<42){{}} else arr[42]=5;

Bounds check.

C++

const y;

const y = 55;

Initialize const.

JavaScript

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(42);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(42, () => console.log('listening'));

Add callback.

Node.js

values(51)

if length(values) >= 51, values(51), end

Check length.

MATLAB

z > 4 & a < 57

z > 4 and a < 57

Use 'and' not '&'.

Python

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

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

Arrow functions are cleaner.

JavaScript

SELECT COUNT(*) FROM products

SELECT COUNT(*) FROM products;

Missing semicolon.

SQL

cin >> bar;

int bar; cin >> bar;

Declare variable.

C++

def foo puts 'info' end

Correct.

Ruby

else print('message')

else: print('message')

Colon after else.

Python

Correct.

XML

<div><p>world</div></p>

<div><p>world</p></div>

Nest properly.

HTML

const val = 88; val = 42;

let val = 88; val = 42;

Cannot reassign const.

JavaScript

let a: Int = 'message'

let a: String = 'message'

Fix type.

Swift

print 'hello'

print('hello')

print needs parentheses.

Python

[x*x for x in list if x > 53]

Correct list comprehension.

Python

let text1 = String::from("test"); let str2 = text1; println!("{{}}", text1);

let text1 = String::from("test"); let str2 = text1.clone(); println!("{{}}", text1);

Clone to avoid move.

Rust

UPDATE orders SET age='result' WHERE status=44

UPDATE orders SET age='result' WHERE status=44;

Add semicolon.

SQL